how would you copy a file?

[Skaperen]

if you use pathlib, testing if file exists is simple:

if filename.exists():
    ...

testing if the file exists is not the issue. i was just describing an example special case reason to build a tree copy. yeah, it is a poor example because cp and rsync both have options to do this, so such a script really isn't needed. what i am trying to focus on is of this were a needed case and you built such a script, when it gets down to copying each individual file, how would other python coders choose to do it? by invoking a copy command or by opening the files and reading and writing all the data?