docs: def visit_If(self, node):
          """Eliminate dead code."""
          # do not optimize ifs that have a block inside so that it doesn't
          # break super().
          if node.find(nodes.Block) is not None:
              return self.generic_visit(node)
          try:
              val = self.visit(node.test).as_const()
          except nodes.Impossible:
              return self.generic_visit(node)
          if val:
              body = node.body
          else:
              body = node.else_
          result = []
          for node in body:
              result.extend(self.visit_list(node))
          return result