         }
     }
 
+    // The actual storage for Data's various representations.
+    // Inlinability strategy: almost everything should be inlinable as forwarding the underlying implementations. (Inlining can also help avoid retain-release traffic around pulling values out of enums.)
     @usableFromInline
     @_frozen
     internal enum _Representation {

            }
        }

        @inlinable
        mutating func replaceSubrange(_ subrange: Range<Index>, with bytes: UnsafeRawPointer?, count cnt: Int) {
            switch self {
            case .empty:

            }
        }

        @inlinable // This is @inlinable as a trivial initializer.
        init(count: Int) {
            if count == 0 {
                self = .empty
