code: def get(self, uri):
          '''Get the content for the bodypart identified by the uri.
          '''
          if uri.startswith('cid:'):
              # Content-ID, so raise exception if not found.
              head, part = self.id_dict[uri[4:]]
              return StringIO.StringIO(part.getvalue())
          if self.loc_dict.has_key(uri):
              head, part = self.loc_dict[uri]
              return StringIO.StringIO(part.getvalue())
          return Nonf get(self, uri):
          '''Get the content for the bodypart identified by the uri.
          '''
          if uri.startswith('cid:'):
              # Content-ID, so raise exception if not found.
              head, part = self.id_dict[uri[4:]]
              return StringIO.StringIO(part.getvalue())
          if self.loc_dict.has_key(uri):
              head, part = self.loc_dict[uri]
              return StringIO.StringIO(part.getvalue())
          return None
docs: Get the content for the bodypart identified by the uri.