<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _cond_update(self, first, second, symbol, maxadd = -1):
 """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."""

        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)