code: def combine_hashes(hashes):
    
    hasher = sha1()
    for h in sorted(hashes):
      h = ensure_binary(h)
      hasher.update(h)
    return hasher.hexdigest() if PY3 else hasher.hexdigest().decode('utf-8')
docs: A simple helper function to combine other hashes.  Sorts the hashes before rolling them in.