code: def eval_debug(self, expression):
          
          code = 'PyJsEvalResult = eval(%s)' % json.dumps(expression)
          self.execute_debug(code)
          return self['PyJsEvalResult']
docs: evaluates expression in current context and returns its value
          as opposed to the (faster) self.execute method, you can use your regular debugger
          to set breakpoints and inspect the generated python code