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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 _tokens_from_patsy(node):
 """ Yields all the individual tokens from within a patsy formula as parsed by patsy.parse_formula.parse_formula. Parameters node : patsy.parse_formula.ParseNode """

    for n in node.args:
        for t in _tokens_from_patsy(n):
            yield t

    if node.token:
        yield node.token