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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 get_grist (value):
 """ Returns the grist of a string. If value is a sequence, does it for every value and returns the result as a sequence. """

    assert is_iterable_typed(value, basestring) or isinstance(value, basestring)
    def get_grist_one (name):
        split = __re_grist_and_value.match (name)
        if not split:
            return ''
        else:
            return split.group (1)

    if isinstance (value, str):
        return get_grist_one (value)
    else:
        return [ get_grist_one (v) for v in value ]