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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def write_to_cache(self, data, filename=''):
        ''' Writes data to file as JSON.  Returns True. '''
        if not filename:
            filename = self.cache_path_cache
        json_data = json.dumps(data)
        with open(filename, 'w') as cache:
            cache.write(json_data)
        return True