<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def build_absolute_uri(self, uri):
 """ Return a fully qualified absolute url for the given uri. """

        request = self.context.get('request', None)

        return (
            request.build_absolute_uri(uri) if request is not None else uri
        )