Return python code for create and execute algo.

def compile(self):
        """Return python code for create and execute algo."""
        result = TEMPLATE

        for rule in self.rules:
            if rule[2]:
                arrow = '=>'
            else:
                arrow = '->'
            repr_rule = repr(rule[0] + arrow + rule[1])

            result += "algo.add_rule({repr_rule})\n".format(repr_rule=repr_rule)

        result += "for line in stdin:\n"
        result += "    print(algo.execute(''.join(line.split())))"
        return result