code: def hash_all(strs, digest=None):
    
    digest = digest or hashlib.sha1()
    for s in strs:
      s = ensure_binary(s)
      digest.update(s)
    return digest.hexdigest() if PY3 else digest.hexdigest().decode('utf-8')
docs: Returns a hash of the concatenation of all the strings in strs.
  
    If a hashlib message digest is not supplied a new sha1 message digest is used.