code: def get_usrgos_g_section(self, section=None):
          
          if section is None:
              section = self.hdrobj.secdflt
          if section is True:
              return self.usrgos
          # Get dict of sections and hdrgos actually used in grouping
          section2hdrgos = cx.OrderedDict(self.get_sections_2d())
          hdrgos_lst = section2hdrgos.get(section, None)
          if hdrgos_lst is not None:
              hdrgos_set = set(hdrgos_lst)
              hdrgos_u = hdrgos_set.intersection(self.hdrgo_is_usrgo)
              hdrgos_h = hdrgos_set.intersection(self.hdrgo2usrgos.keys())
              usrgos = set([u for h in hdrgos_h for u in self.hdrgo2usrgos.get(h)])
              usrgos |= hdrgos_u
              return usrgos
          return set()
docs: Get usrgos in a requested section.