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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 _prodterm(lexer):
 """Return a product term expression."""

    factor = _factor(lexer)
    prodterm_prime = _prodterm_prime(lexer)
    if prodterm_prime is None:
        return factor
    else:
        return ('and', factor, prodterm_prime)