   _precondition(
     newElementIndex == newElementsEndIndex,
     "Cannot replace a slice of a MutableCollection with a slice of a smaller size")
-  */
 }
 
 @available(*, unavailable, renamed: "MutableCollection")

    newElementIndex != newElementsEndIndex {

    self_[selfElementIndex] = slice[newElementIndex]
    selfElementIndex._successorInPlace()
    newElementIndex._successorInPlace()
  }

  _precondition(

  C._Element == Slice_.Iterator.Element,
  C.Index == Slice_.Index
>(self_: inout C, bounds: Range<C.Index>, slice: Slice_) {
  
  self_._failEarlyRangeCheck(bounds, bounds: self_.startIndex..<self_.endIndex)
  
  // FIXME(performance): can we use
  // _withUnsafeMutableBufferPointerIfSupported?  Would that create inout
