code: def section_names(self, ordkey="wall_time"):
          
          section_names = []
  
          # FIXME this is not trivial
          for idx, timer in enumerate(self.timers()):
              if idx == 0:
                  section_names = [s.name for s in timer.order_sections(ordkey)]
                  #check = section_names
                  #else:
                  #  new_set = set( [s.name for s in timer.order_sections(ordkey)])
                  #  section_names.intersection_update(new_set)
                  #  check = check.union(new_set)
  
          #if check != section_names:
          #  print("sections", section_names)
          #  print("check",check)
  
          return section_names
docs: Return the names of sections ordered by ordkey.
          For the time being, the values are taken from the first timer.