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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 make_attrgetter(environment, attribute, postprocess=None):
 """Returns a callable that looks up the given attribute from a passed object with the rules of the environment. Dots are allowed to access attributes of attributes. Integer parts in paths are looked up as integers. """

    if attribute is None:
        attribute = []
    elif isinstance(attribute, string_types):
        attribute = [int(x) if x.isdigit() else x for x in attribute.split('.')]
    else:
        attribute = [attribute]

    def attrgetter(item):
        for part in attribute:
            item = environment.getitem(item, part)

        if postprocess is not None:
            item = postprocess(item)

        return item

    return attrgetter