用 exec 評估語句
>>> code = """for i in range(5):\n print('Hello world!')"""
>>> exec(code)
Hello world!
Hello world!
Hello world!
Hello world!
Hello world!
>>> code = """for i in range(5):\n print('Hello world!')"""
>>> exec(code)
Hello world!
Hello world!
Hello world!
Hello world!
Hello world!