code: def render_include_tree(self):
          
          if self.is_derived():
              env = self.get_build_env()
              if env:
                  for s in self.sources:
                      scanner = self.get_source_scanner(s)
                      if scanner:
                          path = self.get_build_scanner_path(scanner)
                      else:
                          path = None
                      def f(node, env=env, scanner=scanner, path=path):
                          return node.get_found_includes(env, scanner, path)
                      return SCons.Util.render_tree(s, f, 1)
          else:
              return None
docs: Return a text representation, suitable for displaying to the
          user, of the include tree for the sources of this node.