def METHOD_NAME(self, runtime_source_filename):
    '''
    :param runtime_source_filename:
        Something as <ipython-cell-xxx>
    '''
    # Note that we're not interested in the line here, just on knowing if a given filename
    # (from the server) has a mapping for it.
    key = ('has_entry', runtime_source_filename)
    try:
        return self._cache[key]
    except KeyError:
        for _absolute_normalized_filename, mapping in list(self._mappings_to_server.items()):
            for map_entry in mapping:
                if map_entry.runtime_source == runtime_source_filename:
                    self._cache[key] = True
                    return self._cache[key]
        self._cache[key] = False
        return self._cache[key]