code: def _normalize_byte_sig(byte_sig: str) -> str:
          
          if not byte_sig.startswith("0x"):
              byte_sig = "0x" + byte_sig
          if not len(byte_sig) == 10:
              raise ValueError(
                  "Invalid byte signature %s, must have 10 characters", byte_sig
              )
          return byte_sig
docs: Adds a leading 0x to the byte signature if it's not already there.
  
          :param byte_sig: 4-byte signature string
          :return: normalized byte signature string