Convert the given symbolic expression into code.

def _expr2code(self, arg_list, expr):
        """Convert the given symbolic expression into code."""
        code = lambdastr(arg_list, expr)
        function_code = code.split(':')[1].strip()
        #for arg in arg_list:
        #    function_code = function_code.replace(arg.name, 'self.'+arg.name)

        return function_code