code: def changed_roles(self):
          
          ret = []
          g = self.guild
          for overwrite in filter(lambda o: o.type == 'role', self._overwrites):
              role = g.get_role(overwrite.id)
              if role is None:
                  continue
  
              role = copy.copy(role)
              role.permissions.handle_overwrite(overwrite.allow, overwrite.deny)
              ret.append(role)
          return ret
docs: Returns a :class:`list` of :class:`Roles` that have been overridden from
          their default values in the :attr:`Guild.roles` attribute.