code: def _cond_update(self, first, second, symbol, maxadd = -1):
          
          if symbol != "":
              added = 0
              for key in second:
                  if self._symbol_in(symbol, key) and (maxadd == -1 or added <= maxadd):
                      first[key] = second[key]
                      added += 1
          else:
              first.update(second)
docs: Overwrites the keys and values in the first dictionary with those
          of the second as long as the symbol matches part of the key.
  
          :arg maxadd: specifies a limit on the number of entries from the second
            dict that will be added to the first.