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

def put(self, key, value):
    '''Stores the object `value` named by `key`self.
       Writes to both ``cache_datastore`` and ``child_datastore``.
    '''
    self.cache_datastore.put(key, value)
    self.child_datastore.put(key, value)