code: def _update_char_check(self, element, target, docdelta):
          
          if docdelta != 0:
              if (element.docstart <= target and 
                  element.docend >= target - docdelta):
                  return True
              else:
                  return element.absstart > target
          else:
              return element.absstart > target
docs: Checks whether the specified element should have its character indices
          updated as part of real-time updating.