<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def major(self):
 """ Major inbox feed, contains major activities such as notes and images. """

        url = self._subfeed("major")
        if "major" in self.url or "minor" in self.url:
            return self
        if self._major is None:
            self._major = self.__class__(url, pypump=self._pump)
        return self._major