<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def make_parent_bands(self, band, child_bands):
 """ this will determine the grouping bands that it belongs to, recursively 13q21.31 ==> 13, 13q, 13q2, 13q21, 13q21.3, 13q21.31 :param band: :param child_bands: :return: """

        m = re.match(r'([pq][A-H\d]+(?:\.\d+)?)', band)
        if len(band) > 0:
            if m:
                p = str(band[0:len(band)-1])
                p = re.sub(r'\.$', '', p)
                if p is not None:
                    child_bands.add(p)
                    self.make_parent_bands(p, child_bands)
        else:
            child_bands = set()
        return child_bands