Python utils

utils.py

from typing import Iterable 
#from collections import Iterable                            # < py38


def flatten(items):
    """Yield items from any nested iterable;
    
    Source: https://stackoverflow.com/a/40857703
    
    Usage:
      complicated = [[1, [2]], (3, 4, {5, 6}, 7), 8, "9"]              # numbers, strs, nested & mixed
      list(flatten(complicated))
      # [1, 2, 3, 4, 5, 6, 7, 8, '9']
      
    """
    for x in items:
        if isinstance(x, Iterable) and not isinstance(x, (str, bytes)):
            for sub_x in flatten(x):
                yield sub_x
        else:
            yield x