code: def _websocket_mask_python(mask: bytes, data: bytes) -> bytes:
      
      mask_arr = array.array("B", mask)
      unmasked_arr = array.array("B", data)
      for i in range(len(data)):
          unmasked_arr[i] = unmasked_arr[i] ^ mask_arr[i % 4]
      return unmasked_arr.tobytes()
docs: Websocket masking function.
  
      `mask` is a `bytes` object of length 4; `data` is a `bytes` object of any length.
      Returns a `bytes` object of the same length as `data` with the mask applied
      as specified in section 5.3 of RFC 6455.
  
      This pure-python implementation may be replaced by an optimized version when available.