<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def gc(self):
        '''Find the frequency of G and C in the current sequence.'''
        gc = len([base for base in self.seq if base == 'C' or base == 'G'])
        return float(gc) / len(self)