code: def has_true(self, e, extra_constraints=(), solver=None, model_callback=None): #pylint:disable=unused-argument
          
  
          #if self._solver_required and solver is None:
          #   raise BackendError("%s requires a solver for evaluation" % self.__class__.__name__)
  
          return self._has_true(self.convert(e), extra_constraints=extra_constraints, solver=solver, model_callback=model_callback)
docs: Should return True if `e` can possible be True.
  
          :param e:                   The AST.
          :param extra_constraints:   Extra constraints (as ASTs) to add to the solver for this solve.
          :param solver:              A solver, for backends that require it.
          :param model_callback:      a function that will be executed with recovered models (if any)
          :return:                   A boolean