code: def _chk_sections(sections):
          
          if sections:
              assert len(sections[0]) == 2, \
                  "SECTIONS DATA MUST BE A 2-D LIST. FOUND: {S}".format(S=sections)
              for _, hdrgos in sections:
                  chk_goids(hdrgos, "HdrgosSections::_chk_sections()")
docs: Check format of user-provided 'sections' variable