code: def write_hashes(self, arr):
          
          length = len(arr)
          self.write_var_int(length)
          for item in arr:
              ba = bytearray(binascii.unhexlify(item))
              ba.reverse()
              self.write_bytes(ba)
docs: Write an array of hashes to the stream.
  
          Args:
              arr (list): a list of 32 byte hashes.