<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(self, action, version=None):
 """Get the method class handing the given action and version."""

        by_version = self._by_action[action]
        if version in by_version:
            return by_version[version]
        else:
            return by_version[None]