docs: def _indent_decor(lbl):
      """
      does the actual work of indent_func
      """
      def closure_indent(func):
          if util_arg.TRACE:
              @ignores_exc_tb(outer_wrapper=False)
              #@wraps(func)
              def wrp_indent(*args, **kwargs):
                  with util_print.Indenter(lbl):
                      print('    ...trace[in]')
                      ret = func(*args, **kwargs)
                      print('    ...trace[out]')
                      return ret
          else:
              @ignores_exc_tb(outer_wrapper=False)
              #@wraps(func)
              def wrp_indent(*args, **kwargs):
                  with util_print.Indenter(lbl):
                      ret = func(*args, **kwargs)
                      return ret
          wrp_indent_ = ignores_exc_tb(wrp_indent)
          wrp_indent_ = preserve_sig(wrp_indent, func)
          return wrp_indent_
      return closure_indent