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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 _gcd(a=None, b=None, terms=None):
 """Return greatest common divisor using Euclid's Algorithm."""

    if terms:
        return reduce(lambda a, b: _gcd(a, b), terms)
    else:
        while b:
            (a, b) = (b, a % b)
        return a