You can also do something like this:
<action application="set" data="execute_on_answer=execute_extension HANDLE_ANSWER"/>

And then define your answer handler extension:
<extension name="Handle Answered Calls">
  <condition field="destination_number" expression="^HANDLE_ANSWER$"/>
    <action application="python" data="/path/to/my/python/script.py"/>
    <action application="sched_hangup" data="+300 TIMED_OUT"/>
    <action application="log" data="INFO You can do all sorts of stuff"/>
    <!-- If this extension was called with 'execute_extension' then it will go back to the calling extension when done... -->
  </condition>
</extension>