<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_cache_key(self, **kwargs):
 """ Take this task's configured ``significant_kwargs`` and build a hash that all equivalent task calls will match. Takes in kwargs and returns a string. To change the way the cache key is generated or do more in-depth processing, override this method. """

        m = md5()
        for significant_kwarg in self.significant_kwargs:
            key, to_str = significant_kwarg
            try:
                m.update(to_str(kwargs[key]))
            except (TypeError, UnicodeEncodeError):
                # Python 3.x strings aren't accepted by hash.update().
                # String should be byte-encoded first.
                m.update(to_str(kwargs[key]).encode('utf-8'))

        if hasattr(self, 'cache_prefix'):
            cache_prefix = self.cache_prefix
        else:
            cache_prefix = '%s.%s' % (self.__module__, self.__name__)
        return '%s:%s' % (cache_prefix, m.hexdigest())