<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def hash_tuple(val, encoding='utf8', hash_key=None):
 """ Hash a single tuple efficiently Parameters val : single tuple encoding : string, default 'utf8' hash_key : string key to encode, default to _default_hash_key Returns ------- hash """

    hashes = (_hash_scalar(v, encoding=encoding, hash_key=hash_key)
              for v in val)

    h = _combine_hash_arrays(hashes, len(val))[0]

    return h