code: def get_sections(self, hdrgo, dflt_section=True):
          
          dflt_list = []
          # If the hdrgo is not in a section, return the default name for a section
          if dflt_section:
              dflt_list = [self.secdflt]
          return self.hdrgo2sections.get(hdrgo, dflt_list)
docs: Given a header GO, return the sections that contain it.