Organize extension functions.

Author: Matthew Judy

Sources/Shared/ClosedRange+Overlap.swift

@@ -1,5 +1,5 @@
 //
-//  ClosedRange+Covers.swift
+//  ClosedRange+Overlap.swift
 //
 //  Created by Matthew Judy on 12/4/22.
 //

Sources/Shared/Collection+.swift

@@ -1,8 +1,39 @@
 //
-//  File.swift
-//  
+//  Collection+.swift
 //
 //  Created by Matthew Judy on 12/4/23.
 //
 
 import Foundation
+
+
+extension Collection
+{
+    public var lastIndex: Int?
+    {
+        guard ( self.count > 0 ) else { return nil }
+        return (self.count - 1)
+    }
+
+
+    public func count(where test: (Element) throws -> Bool) rethrows -> Int {
+        return try self.filter(test).count
+    }
+
+    
+    public func stride(from: Index? = nil, through: Index? = nil, by: Int) -> AnySequence<Element>
+    {
+        var index    = from    ?? self.startIndex
+        let endIndex = through ?? self.endIndex
+
+        return AnySequence(
+            AnyIterator
+            {
+                guard (index < endIndex) else { return nil }
+                defer { index = self.index(index, offsetBy: by, limitedBy: endIndex) ?? endIndex }
+                return self[index]
+            }
+        )
+    }
+}
+

Sources/Shared/RangeReplaceableCollection+.swift

@@ -1,5 +1,5 @@
 //
-//  RangeReplaceableCollection+Every.swift
+//  RangeReplaceableCollection+.swift
 //
 //  Created by Matthew Judy on 12/26/22.
 //

Sources/Shared/Sequence+.swift

@@ -1,5 +1,5 @@
 //
-//  Sequence+Sum.swift
+//  Sequence+.swift
 //  
 //  Created by Matthew Judy on 2022-12-01.
 //
@@ -22,3 +22,4 @@ extension Sequence where Element: Hashable
         return !(self.contains { !(set.insert($0).inserted) })
     }
 }
+