How to copy files from subfolders into one folder

[DeaD_EyE]

You already know, I like the abstraction of pathlib.

import shutil
from pathlib import Path


src_path = Path("U:\\collections\\2019_input")
out_path = Path("U:\\collections\\2019_output")


for filename in src_path.rglob('*'):
    target_file = out_path / filename.name
    if target_file.exists():
        print('File', target_file, 'exists already. Skipping...')
        continue
    print(filename, target_file)
    # shutil.copy2(filename, target_file)

Code haven't been tested. You have to be careful, pathlib got some additions, which are not in older versions available.
I use Python 3.7.4.