docs: def istrue(self, *args):
          """Strict test for 'true' value test. If multiple args are provided it will
          test them all.
              ISTRUE:true
  
          %{ISTRUE:true} -> 'True'
          """
          def is_true(val):
              if val is True:
                  return True
              val = str(val).lower().strip()
              return val in ('true', 'yes', '1')
          return all(self._arg_factory(is_true, args))