     /// - parameter rhs: The base sequence.
     ///
     /// - returns: A new sequence constructed by appending the new element to the beginning of the base sequence.
-    public static func + (lhs: Iterator.Element, rhs: Self) -> AnySequence<Iterator.Element> {
+    internal static func + (lhs: Iterator.Element, rhs: Self) -> AnySequence<Iterator.Element> {
         
         let oneElementSequence = AnySequence([lhs])
         

    /// - parameter rhs: The element to append.
    ///
    /// - returns: A new sequence constructed by appending the new element to the end of the base sequence.
    public static func + (lhs: Self, rhs: Iterator.Element) -> AnySequence<Iterator.Element> {
        
        let oneElementSequence = AnySequence([rhs])
        

//
//

extension Sequence {
    
    /// Concatenates the sequences.
    ///
