pip watercress source proxy
For some reason, the access to the official pypi is unstable, very slow and even some cannot be accessed from time to time
Python
Python direct assignment, shallow copy and deep copy analysis
Direct assignment: In fact, it is a reference to the object. Shallow copy (copy): copies the parent object and does not copy the internal child objects of the object. Deep copy (deepcopy): The deepcopy method of the copy module completely copies the parent object and its child objects.