code: def pop_scope(self, aliases, frame):
          
          for name, alias in aliases.iteritems():
              self.writeline('l_%s = %s' % (name, alias))
          to_delete = set()
          for name in frame.identifiers.declared_locally:
              if name not in aliases:
                  to_delete.add('l_' + name)
          if to_delete:
              # we cannot use the del statement here because enclosed
              # scopes can trigger a SyntaxError:
              #   a = 42; b = lambda: a; del a
              self.writeline(' = '.join(to_delete) + ' = missing')
docs: Restore all aliases and delete unused variables.