code: func WithBytesAndArg(s string, arg interface{}, fn BytesAndArgFn) {
  	fn(Bytes(s), arg)
  }
docs: // WithBytesAndArg converts a string to a byte slice with zero heap memory allocations,
  // and calls a function to process the byte slice alongside one argument. It is the
  // caller's responsibility to make sure the callback function passed in does not modify
  // the byte slice in any way, and holds no reference to the byte slice after the function
  // returns.