1 初始化模块
模块包含可执行语句及函数定义。这些语句用于初始化模块，且仅在 import 语句 第一次 遇到模块名时执行
2 为了保证运行效率，每次解释器会话只导入一次模块。如果更改了模块内容，必须重启解释器；仅交互测试一个模块时，也可以使用 importlib.reload()，例如 import importlib; importlib.reload(modulename)。
3 Can you import a module more than once in Python?
Yes, you can import a module more than once in Python. However, the module will only be loaded and executed once during the entire runtime of your program, regardless of how many times you import it.
When a module is imported, Python checks if the module has already been imported and stored in the cache. If it has, Python simply references the already loaded module instead of executing the module's code again.
解释: 无论导入模块多少次, 仅被加载和执行一次.
标签：importlib,Python,module,导入,模块,import From： https://www.cnblogs.com/tslam/p/18116154