diff --git a/Package.swift b/Package.swift
index 6e1ffe4..7355d60 100644
--- a/Package.swift
+++ b/Package.swift
@@ -19,6 +19,9 @@ let package = Package(
             dependencies: []),
         .testTarget(
             name: "FirebladeECSTests",
+            dependencies: ["FirebladeECS"]),
+        .testTarget(
+            name: "FirebladeECSPerformanceTests",
             dependencies: ["FirebladeECS"])
     ]
 )
diff --git a/Sources/FirebladeECS/TypedFamily1.swift b/Sources/FirebladeECS/TypedFamily1.swift
index 301525c..e91603f 100644
--- a/Sources/FirebladeECS/TypedFamily1.swift
+++ b/Sources/FirebladeECS/TypedFamily1.swift
@@ -52,11 +52,7 @@ public struct FamilyEntitiesAndComponents1<A>: EntityComponentsSequenceProtocol
     }
 
     public mutating func next() -> (Entity, A)? {
-        guard let entityId = memberIdsIterator.next() else {
-            return nil
-        }
-
-        guard
+        guard let entityId = memberIdsIterator.next(),
             let entity = nexus.get(entity: entityId),
             let compA: A = nexus.get(for: entityId)
             else {
diff --git a/Sources/FirebladeECS/UnorderedSparseSet.swift b/Sources/FirebladeECS/UnorderedSparseSet.swift
index 489d797..1f98579 100644
--- a/Sources/FirebladeECS/UnorderedSparseSet.swift
+++ b/Sources/FirebladeECS/UnorderedSparseSet.swift
@@ -5,7 +5,7 @@
 //  Created by Christian Treffs on 30.10.17.
 //
 
-public class UnorderedSparseSet<Element> {
+open class UnorderedSparseSet<Element> {
     public typealias Index = Int
     public typealias Key = Int
 
@@ -14,8 +14,8 @@ public class UnorderedSparseSet<Element> {
         public let element: Element
     }
 
-    internal var dense: ContiguousArray<Entry>
-    internal var sparse: [Index: Key]
+    public private(set) var dense: ContiguousArray<Entry>
+    public private(set) var sparse: [Index: Key]
 
     public init() {
         sparse = [Index: Key]()
@@ -30,6 +30,7 @@ public class UnorderedSparseSet<Element> {
     public var isEmpty: Bool { return dense.isEmpty }
     public var capacity: Int { return sparse.count }
 
+    @inlinable
     public func contains(_ key: Key) -> Bool {
         return find(at: key) != nil
     }
@@ -58,6 +59,7 @@ public class UnorderedSparseSet<Element> {
     ///
     /// - Parameter key: the key
     /// - Returns: the element or nil of key not found.
+    @inlinable
     public func get(at key: Key) -> Element? {
         guard let (_, element) = find(at: key) else {
             return nil
@@ -66,6 +68,7 @@ public class UnorderedSparseSet<Element> {
         return element
     }
 
+    @inlinable
     public func get(unsafeAt key: Key) -> Element {
         return find(at: key).unsafelyUnwrapped.1
     }
@@ -108,7 +111,8 @@ public class UnorderedSparseSet<Element> {
         return dense.removeLast()
     }
 
-    private func find(at key: Key) -> (Int, Element)? {
+    @inlinable
+    public func find(at key: Key) -> (Int, Element)? {
         guard let denseIndex = sparse[key], denseIndex < count else {
             return nil
         }
diff --git a/Tests/FirebladeECSPerformanceTests/Base.swift b/Tests/FirebladeECSPerformanceTests/Base.swift
new file mode 100644
index 0000000..63db0ff
--- /dev/null
+++ b/Tests/FirebladeECSPerformanceTests/Base.swift
@@ -0,0 +1,71 @@
+//
+//  Base.swift
+//  FirebladeECSTests
+//
+//  Created by Christian Treffs on 09.10.17.
+//
+
+import FirebladeECS
+
+class EmptyComponent: Component { }
+
+class Name: Component {
+	var name: String
+	init(name: String) {
+		self.name = name
+	}
+}
+
+class Position: Component {
+	var x: Int
+	var y: Int
+	init(x: Int, y: Int) {
+		self.x = x
+		self.y = y
+	}
+}
+
+class Velocity: Component {
+	var a: Float
+	init(a: Float) {
+		self.a = a
+	}
+}
+
+class Party: Component {
+	var partying: Bool
+	init(partying: Bool) {
+		self.partying = partying
+	}
+}
+
+class Color: Component {
+    var r: UInt8 = 0
+    var g: UInt8 = 0
+    var b: UInt8 = 0
+}
+
+class ExampleSystem {
+	private let family: TypedFamily2<Position, Velocity>
+
+	init(nexus: Nexus) {
+		family = nexus.family(requiresAll: Position.self, Velocity.self, excludesAll: EmptyComponent.self)
+	}
+
+	func update(deltaT: Double) {
+        family.forEach { (position: Position, velocity: Velocity) in
+			position.x *= 2
+			velocity.a *= 2
+
+        }
+
+	}
+
+}
+
+
+final class SingleGameState: SingleComponent {
+    var shouldQuit: Bool = false
+    var playerHealth: Int = 67
+    
+}
diff --git a/Tests/FirebladeECSPerformanceTests/ComponentPerformanceTests.swift b/Tests/FirebladeECSPerformanceTests/ComponentPerformanceTests.swift
new file mode 100644
index 0000000..dea2bb8
--- /dev/null
+++ b/Tests/FirebladeECSPerformanceTests/ComponentPerformanceTests.swift
@@ -0,0 +1,33 @@
+//
+//  ComponentPerformanceTests.swift
+//  FirebladeECSPerformanceTests
+//
+//  Created by Christian Treffs on 14.02.19.
+//
+
+@testable import FirebladeECS
+import XCTest
+
+class ComponentTests: XCTestCase {
+
+    func testMeasureStaticComponentIdentifier() {
+        let number: Int = 10_000
+        measure {
+            for _ in 0..<number {
+                let id = Position.identifier
+                _ = id
+            }
+        }
+    }
+    
+    func testMeasureComponentIdentifier() {
+        let number: Int = 10_000
+        let pos = Position(x: 1, y: 2)
+        measure {
+            for _ in 0..<number {
+                let id = pos.identifier
+                _ = id
+            }
+        }
+    }
+}
diff --git a/Tests/FirebladeECSPerformanceTests/HashingPerformanceTests.swift b/Tests/FirebladeECSPerformanceTests/HashingPerformanceTests.swift
new file mode 100644
index 0000000..af535da
--- /dev/null
+++ b/Tests/FirebladeECSPerformanceTests/HashingPerformanceTests.swift
@@ -0,0 +1,42 @@
+//
+//  HashingPerformanceTests.swift
+//  FirebladeECSPerformanceTests
+//
+//  Created by Christian Treffs on 14.02.19.
+//
+
+import XCTest
+import FirebladeECS
+
+class HashingPerformanceTests: XCTestCase {
+    
+    func testMeasureCombineHash() {
+        let a: Set<Int> = Set<Int>([14_561_291, 26_451_562, 34_562_182, 488_972_556, 5_128_426_962, 68_211_812])
+        let b: Set<Int> = Set<Int>([1_083_838, 912_312, 83_333, 71_234_555, 4_343_234])
+        let c: Set<Int> = Set<Int>([3_410_346_899_765, 90_000_002, 12_212_321, 71, 6_123_345_676_543])
+        
+        let input: ContiguousArray<Int> = ContiguousArray<Int>(arrayLiteral: a.hashValue, b.hashValue, c.hashValue)
+        measure {
+            for _ in 0..<1_000_000 {
+                let hashRes: Int = FirebladeECS.hash(combine: input)
+                _ = hashRes
+            }
+        }
+    }
+    
+    func testMeasureSetOfSetHash() {
+        let a: Set<Int> = Set<Int>([14_561_291, 26_451_562, 34_562_182, 488_972_556, 5_128_426_962, 68_211_812])
+        let b: Set<Int> = Set<Int>([1_083_838, 912_312, 83_333, 71_234_555, 4_343_234])
+        let c: Set<Int> = Set<Int>([3_410_346_899_765, 90_000_002, 12_212_321, 71, 6_123_345_676_543])
+        
+        let input = Set<Set<Int>>(arrayLiteral: a, b, c)
+        measure {
+            for _ in 0..<1_000_000 {
+                let hash: Int = input.hashValue
+                _ = hash
+            }
+        }
+    }
+    
+    
+}
diff --git a/Tests/FirebladeECSTests/TypedFamilyPerformanceTests.swift b/Tests/FirebladeECSPerformanceTests/TypedFamilyPerformanceTests.swift
similarity index 94%
rename from Tests/FirebladeECSTests/TypedFamilyPerformanceTests.swift
rename to Tests/FirebladeECSPerformanceTests/TypedFamilyPerformanceTests.swift
index abada10..517fefe 100644
--- a/Tests/FirebladeECSTests/TypedFamilyPerformanceTests.swift
+++ b/Tests/FirebladeECSPerformanceTests/TypedFamilyPerformanceTests.swift
@@ -31,6 +31,25 @@ class TypedFamilyPerformanceTests: XCTestCase {
         super.tearDown()
     }
     
+    func testMeasureTraitMatching() {
+        
+        let a = nexus.create(entity: "a")
+        a.assign(Position(x: 1, y: 2))
+        a.assign(Name(name: "myName"))
+        a.assign(Velocity(a: 3.14))
+        a.assign(EmptyComponent())
+        
+        let isMatch = nexus.family(requiresAll: Position.self, Velocity.self,
+                                   excludesAll: Party.self)
+        
+        measure {
+            for _ in 0..<10_000 {
+                let success = isMatch.canBecomeMember(a)
+                XCTAssert(success)
+            }
+        }
+    }
+    
     func testPerformanceTypedFamilyEntities() {
         let family = nexus.family(requires: Position.self, excludesAll: Party.self)
         
diff --git a/Tests/FirebladeECSTests/Base.swift b/Tests/FirebladeECSTests/Base.swift
index 63db0ff..0c122a7 100644
--- a/Tests/FirebladeECSTests/Base.swift
+++ b/Tests/FirebladeECSTests/Base.swift
@@ -10,33 +10,33 @@ import FirebladeECS
 class EmptyComponent: Component { }
 
 class Name: Component {
-	var name: String
-	init(name: String) {
-		self.name = name
-	}
+    var name: String
+    init(name: String) {
+        self.name = name
+    }
 }
 
 class Position: Component {
-	var x: Int
-	var y: Int
-	init(x: Int, y: Int) {
-		self.x = x
-		self.y = y
-	}
+    var x: Int
+    var y: Int
+    init(x: Int, y: Int) {
+        self.x = x
+        self.y = y
+    }
 }
 
 class Velocity: Component {
-	var a: Float
-	init(a: Float) {
-		self.a = a
-	}
+    var a: Float
+    init(a: Float) {
+        self.a = a
+    }
 }
 
 class Party: Component {
-	var partying: Bool
-	init(partying: Bool) {
-		self.partying = partying
-	}
+    var partying: Bool
+    init(partying: Bool) {
+        self.partying = partying
+    }
 }
 
 class Color: Component {
@@ -45,27 +45,78 @@ class Color: Component {
     var b: UInt8 = 0
 }
 
-class ExampleSystem {
-	private let family: TypedFamily2<Position, Velocity>
-
-	init(nexus: Nexus) {
-		family = nexus.family(requiresAll: Position.self, Velocity.self, excludesAll: EmptyComponent.self)
-	}
-
-	func update(deltaT: Double) {
-        family.forEach { (position: Position, velocity: Velocity) in
-			position.x *= 2
-			velocity.a *= 2
-
-        }
-
-	}
-
-}
-
 
 final class SingleGameState: SingleComponent {
     var shouldQuit: Bool = false
     var playerHealth: Int = 67
     
 }
+
+
+class ExampleSystem {
+    private let family: TypedFamily2<Position, Velocity>
+    
+    init(nexus: Nexus) {
+        family = nexus.family(requiresAll: Position.self, Velocity.self, excludesAll: EmptyComponent.self)
+    }
+    
+    func update(deltaT: Double) {
+        family.forEach { (position: Position, velocity: Velocity) in
+            position.x *= 2
+            velocity.a *= 2
+            
+        }
+        
+    }
+    
+}
+
+
+class ColorSystem {
+    
+    let nexus: Nexus
+    lazy var colors = nexus.family(requires: Color.self)
+    
+    init(nexus: Nexus) {
+        self.nexus = nexus
+    }
+    
+    func update() {
+        colors
+            .forEach { (color: Color) in
+                color.r = 1
+                color.g = 2
+                color.b = 3
+        }
+    }
+}
+
+class PositionSystem {
+    let positions: TypedFamily1<Position>
+    
+    var velocity: Double = 4.0
+    
+    init(nexus: Nexus) {
+        positions = nexus.family(requires: Position.self)
+    }
+    
+    func randNorm() -> Double {
+        return 4.0
+    }
+    
+    func update() {
+        positions
+            .forEach { [unowned self](pos: Position) in
+                
+                let deltaX: Double = self.velocity * ((self.randNorm() * 2) - 1)
+                let deltaY: Double = self.velocity * ((self.randNorm() * 2) - 1)
+                let x = pos.x + Int(deltaX)
+                let y = pos.y + Int(deltaY)
+                
+                pos.x = x
+                pos.y = y
+        }
+    }
+    
+}
+
diff --git a/Tests/FirebladeECSTests/ComponentTests.swift b/Tests/FirebladeECSTests/ComponentTests.swift
index c1b9a39..be1868f 100644
--- a/Tests/FirebladeECSTests/ComponentTests.swift
+++ b/Tests/FirebladeECSTests/ComponentTests.swift
@@ -10,16 +10,6 @@ import XCTest
 
 class ComponentTests: XCTestCase {
 
-    override func setUp() {
-        super.setUp()
-        // Put setup code here. This method is called before the invocation of each test method in the class.
-    }
-
-    override func tearDown() {
-        // Put teardown code here. This method is called after the invocation of each test method in the class.
-        super.tearDown()
-    }
-
 	func testComponentIdentifier() {
 		let p1 = Position(x: 1, y: 2)
 		XCTAssert(p1.identifier == Position.identifier)
@@ -30,25 +20,5 @@ class ComponentTests: XCTestCase {
 		XCTAssert(Velocity.identifier != Position.identifier)
 	}
 
-	func testMeasureStaticComponentIdentifier() {
-		let number: Int = 10_000
-		measure {
-			for _ in 0..<number {
-				let id = Position.identifier
-				_ = id
-			}
-		}
-	}
-
-	func testMeasureComponentIdentifier() {
-		let number: Int = 10_000
-		let pos = Position(x: 1, y: 2)
-		measure {
-			for _ in 0..<number {
-				let id = pos.identifier
-				_ = id
-			}
-		}
-	}
 
 }
diff --git a/Tests/FirebladeECSTests/EntityTests.swift b/Tests/FirebladeECSTests/EntityTests.swift
index b1ab939..539ae2b 100644
--- a/Tests/FirebladeECSTests/EntityTests.swift
+++ b/Tests/FirebladeECSTests/EntityTests.swift
@@ -10,16 +10,6 @@ import XCTest
 
 class EntityTests: XCTestCase {
 
-    override func setUp() {
-        super.setUp()
-        // Put setup code here. This method is called before the invocation of each test method in the class.
-    }
-
-    override func tearDown() {
-        // Put teardown code here. This method is called after the invocation of each test method in the class.
-        super.tearDown()
-    }
-
 	func testEntityIdentifierAndIndex() {
 
 		let min: EntityIndex = EntityIdentifier(EntityIdentifier.min).index
diff --git a/Tests/FirebladeECSTests/FamilyTests.swift b/Tests/FirebladeECSTests/FamilyTests.swift
index 8f04d3b..3c3f000 100644
--- a/Tests/FirebladeECSTests/FamilyTests.swift
+++ b/Tests/FirebladeECSTests/FamilyTests.swift
@@ -22,6 +22,12 @@ class FamilyTests: XCTestCase {
         super.tearDown()
     }
     
+    func createDefaultEntity(name: String?) {
+        let e = nexus.create(entity: name)
+        e.assign(Position(x: 1, y: 2))
+        e.assign(Color())
+    }
+    
     func testFamilyCreation() {
         
         let family = nexus.family(requires: Position.self,
@@ -53,47 +59,30 @@ class FamilyTests: XCTestCase {
     func testFamilyAbandoned() {
         
         XCTAssertEqual(nexus.familyMembersByTraits.keys.count, 0)
-        
         _ = nexus.family(requires: Position.self)
-        
         XCTAssertEqual(nexus.familyMembersByTraits.keys.count, 1)
-        
         let entity = nexus.create(entity: "eimer")
         entity.assign(Position(x: 1, y: 1))
-        
         XCTAssertEqual(nexus.familyMembersByTraits.keys.count, 1)
-        
         entity.remove(Position.self)
-        
-        // FIXME: the family trait should vanish when no entity with revlevant component is present anymore
-        
         XCTAssertEqual(nexus.familyMembersByTraits.keys.count, 1)
-        
         nexus.destroy(entity: entity)
-        
         XCTAssertEqual(nexus.familyMembersByTraits.keys.count, 1)
         
     }
     
     func testFamilyLateMember() {
-        
         let eEarly = nexus.create(entity: "eary").assign(Position(x: 1, y: 2))
-        
         XCTAssertEqual(nexus.familyMembersByTraits.keys.count, 0)
-        
         let family = nexus.family(requires: Position.self)
-        
         XCTAssertEqual(nexus.familyMembersByTraits.keys.count, 1)
-        
         let eLate = nexus.create(entity: "late").assign(Position(x: 1, y: 2))
-        
         XCTAssertTrue(family.isMember(eEarly))
         XCTAssertTrue(family.isMember(eLate))
         
     }
     
     func testFamilyExchange() {
-        
         let number: Int = 10
         
         for i in 0..<number {
@@ -153,12 +142,6 @@ class FamilyTests: XCTestCase {
         }
     }
     
-    func createDefaultEntity(name: String?) {
-        let e = nexus.create(entity: name)
-        e.assign(Position(x: 1, y: 2))
-        e.assign(Color())
-    }
-    
     func testFamilyBulkDestroy() {
         let count = 10_000
         
diff --git a/Tests/FirebladeECSTests/FamilyTraitsTests.swift b/Tests/FirebladeECSTests/FamilyTraitsTests.swift
index d6f61fd..fde1cf9 100644
--- a/Tests/FirebladeECSTests/FamilyTraitsTests.swift
+++ b/Tests/FirebladeECSTests/FamilyTraitsTests.swift
@@ -54,23 +54,4 @@ class FamilyTraitsTests: XCTestCase {
 
     }
 
-    func testMeasureTraitMatching() {
-
-        let a = nexus.create(entity: "a")
-        a.assign(Position(x: 1, y: 2))
-        a.assign(Name(name: "myName"))
-        a.assign(Velocity(a: 3.14))
-        a.assign(EmptyComponent())
-
-        let isMatch = nexus.family(requiresAll: Position.self, Velocity.self,
-                                   excludesAll: Party.self)
-
-        measure {
-            for _ in 0..<10_000 {
-                let success = isMatch.canBecomeMember(a)
-                XCTAssert(success)
-            }
-        }
-    }
-
 }
diff --git a/Tests/FirebladeECSTests/HashingTests.swift b/Tests/FirebladeECSTests/HashingTests.swift
index 762efdc..4795cd9 100644
--- a/Tests/FirebladeECSTests/HashingTests.swift
+++ b/Tests/FirebladeECSTests/HashingTests.swift
@@ -9,78 +9,47 @@
 import XCTest
 
 class HashingTests: XCTestCase {
-
-	func testCollisionsInCritialRange() {
-
-		var hashSet: Set<Int> = Set<Int>()
-
-		var range: CountableRange<EntityIdentifier> = 0 ..< 1_000_000
-
-		let maxComponents: Int = 1000
-		let components: [Int] = (0..<maxComponents).map { _ in makeComponent() }
-
-		var index: Int = 0
-		while let eId: EntityIdentifier = range.popLast() {
-
-			let entityId: EntityIdentifier = eId
-			let c = (index % maxComponents)
-			index += 1
-
-			let cH: ComponentTypeHash = components[c]
-
-			let h: Int = EntityComponentHash.compose(entityId: entityId, componentTypeHash: cH)
-
-			let (collisionFree, _) = hashSet.insert(h)
-			XCTAssert(collisionFree)
-
-			XCTAssert(EntityComponentHash.decompose(h, with: cH) == entityId)
-			XCTAssert(EntityComponentHash.decompose(h, with: entityId) == cH)
-		}
-	}
-
-	func testMeasureCombineHash() {
-		let a: Set<Int> = Set<Int>([14_561_291, 26_451_562, 34_562_182, 488_972_556, 5_128_426_962, 68_211_812])
-		let b: Set<Int> = Set<Int>([1_083_838, 912_312, 83_333, 71_234_555, 4_343_234])
-		let c: Set<Int> = Set<Int>([3_410_346_899_765, 90_000_002, 12_212_321, 71, 6_123_345_676_543])
-
-		let input: ContiguousArray<Int> = ContiguousArray<Int>(arrayLiteral: a.hashValue, b.hashValue, c.hashValue)
-		measure {
-			for _ in 0..<1_000_000 {
-				let hashRes: Int = FirebladeECS.hash(combine: input)
-				_ = hashRes
-			}
-		}
-	}
-
-	func testMeasureSetOfSetHash() {
-		let a: Set<Int> = Set<Int>([14_561_291, 26_451_562, 34_562_182, 488_972_556, 5_128_426_962, 68_211_812])
-		let b: Set<Int> = Set<Int>([1_083_838, 912_312, 83_333, 71_234_555, 4_343_234])
-		let c: Set<Int> = Set<Int>([3_410_346_899_765, 90_000_002, 12_212_321, 71, 6_123_345_676_543])
-
-		let input = Set<Set<Int>>(arrayLiteral: a, b, c)
-		measure {
-			for _ in 0..<1_000_000 {
-				let hash: Int = input.hashValue
-				_ = hash
-			}
-		}
-	}
-
+    
+    func makeComponent() -> Int {
+        let upperBound: Int = 44
+        let high = UInt(arc4random()) << UInt(upperBound)
+        let low = UInt(arc4random())
+        assert(high.leadingZeroBitCount < 64 - upperBound)
+        assert(high.trailingZeroBitCount >= upperBound)
+        assert(low.leadingZeroBitCount >= 32)
+        assert(low.trailingZeroBitCount <= 32)
+        let rand: UInt = high | low
+        let cH = Int(bitPattern: rand)
+        return cH
+    }
+    
+    func testCollisionsInCritialRange() {
+        
+        var hashSet: Set<Int> = Set<Int>()
+        
+        var range: CountableRange<EntityIdentifier> = 0 ..< 1_000_000
+        
+        let maxComponents: Int = 1000
+        let components: [Int] = (0..<maxComponents).map { _ in makeComponent() }
+        
+        var index: Int = 0
+        while let eId: EntityIdentifier = range.popLast() {
+            
+            let entityId: EntityIdentifier = eId
+            let c = (index % maxComponents)
+            index += 1
+            
+            let cH: ComponentTypeHash = components[c]
+            
+            let h: Int = EntityComponentHash.compose(entityId: entityId, componentTypeHash: cH)
+            
+            let (collisionFree, _) = hashSet.insert(h)
+            XCTAssert(collisionFree)
+            
+            XCTAssert(EntityComponentHash.decompose(h, with: cH) == entityId)
+            XCTAssert(EntityComponentHash.decompose(h, with: entityId) == cH)
+        }
+    }
+    
 }
 
-// MARK: - helper
-extension HashingTests {
-
-	func makeComponent() -> Int {
-		let upperBound: Int = 44
-		let high = UInt(arc4random()) << UInt(upperBound)
-		let low = UInt(arc4random())
-		assert(high.leadingZeroBitCount < 64 - upperBound)
-		assert(high.trailingZeroBitCount >= upperBound)
-		assert(low.leadingZeroBitCount >= 32)
-		assert(low.trailingZeroBitCount <= 32)
-		let rand: UInt = high | low
-		let cH = Int(bitPattern: rand)
-		return cH
-	}
-}
diff --git a/Tests/FirebladeECSTests/SystemsTests.swift b/Tests/FirebladeECSTests/SystemsTests.swift
index 38f5424..0006205 100644
--- a/Tests/FirebladeECSTests/SystemsTests.swift
+++ b/Tests/FirebladeECSTests/SystemsTests.swift
@@ -128,51 +128,3 @@ class SystemsTests: XCTestCase {
     }
     
 }
-
-class ColorSystem {
-    
-    let nexus: Nexus
-    lazy var colors = nexus.family(requires: Color.self)
-    
-    init(nexus: Nexus) {
-        self.nexus = nexus
-    }
-    
-    func update() {
-        colors
-            .forEach { (color: Color) in
-                color.r = 1
-                color.g = 2
-                color.b = 3
-        }
-    }
-}
-
-class PositionSystem {
-    let positions: TypedFamily1<Position>
-    
-    var velocity: Double = 4.0
-    
-    init(nexus: Nexus) {
-        positions = nexus.family(requires: Position.self)
-    }
-    
-    func randNorm() -> Double {
-        return 4.0
-    }
-    
-    func update() {
-        positions
-            .forEach { [unowned self](pos: Position) in
-            
-            let deltaX: Double = self.velocity * ((self.randNorm() * 2) - 1)
-            let deltaY: Double = self.velocity * ((self.randNorm() * 2) - 1)
-            let x = pos.x + Int(deltaX)
-            let y = pos.y + Int(deltaY)
-            
-            pos.x = x
-            pos.y = y
-        }
-    }
-    
-}