<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(cls, id_or_name, *, parent=None, namespace=None):
 """Get an entity by id. Parameters: id_or_name(int or str):
 The entity's id. parent(anom.Key, optional):
 The entity's parent Key. namespace(str, optional):
 The entity's namespace. Returns: Model: An entity or ``None`` if the entity doesn't exist in Datastore. """

        return Key(cls, id_or_name, parent=parent, namespace=namespace).get()