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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def hash_names(names, hash_function=None):
 """Return the hash of an iterable of strings, or a dict if multiple hash functions given. :param iter[str] names: An iterable of strings :param hash_function: A hash function or list of hash functions, like :func:`hashlib.md5` or :func:`hashlib.sha512` :rtype: str """

    hash_function = hash_function or hashlib.md5
    names_bytes = _names_to_bytes(names)
    return hash_function(names_bytes).hexdigest()