code: def logo_url(self):
          
          if self.logo_ext:
              return '/api/files/{bucket}/{key}'.format(
                  bucket=current_app.config['COMMUNITIES_BUCKET_UUID'],
                  key='{0}/logo.{1}'.format(self.id, self.logo_ext),
              )
          return None
docs: Get URL to collection logo.
  
          :returns: Path to community logo.
          :rtype: str