     }
     append(_StringGutsSlice(other))
   }
-  
+
   @inline(never)
   @_effects(readonly)
   private func _foreignConvertedToSmall() -> _SmallString {

      self = _StringGuts(_SmallString(smolSelf, appending: smolOther)!)
      return
    }
    
    prepareForAppendInPlace(totalCount: totalCount, otherUTF8Count: otherCount)

    if slicedOther.isFastUTF8 {

    _internalInvariant(smol._guts.isSmall)
    return smol._guts.asSmall
  }

  private func _convertedToSmall() -> _SmallString {
    _internalInvariant(utf8Count <= _SmallString.capacity)
    if _fastPath(isSmall) {
