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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 check_extras(dist, attr, value):
 """Verify that extras_require mapping is valid"""

    try:
        list(itertools.starmap(_check_extra, value.items()))
    except (TypeError, ValueError, AttributeError):
        raise DistutilsSetupError(
            "'extras_require' must be a dictionary whose values are "
            "strings or lists of strings containing valid project/version "
            "requirement specifiers."
        )