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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 _parse_band(cls, kw):
 """Returns photometric band from inifile keyword """

        m = re.search('([a-zA-Z0-9]+)(_\d+)?', kw)
        if m:
            if m.group(1) in cls._not_a_band:
                return None
            else:
                return m.group(1)