Recursive dictionary merge in Python 3

dict_merge.py

# -*- coding: utf-8 -*-

import collections


def dict_merge(dct: dict, merge_dct: dict):
    """ Recursive dict merge. Inspired by :meth:``dict.update()``, instead of
    updating only top-level keys, dict_merge recurses down into dicts nested
    to an arbitrary depth, updating keys. The ``merge_dct`` is merged into
    ``dct``.

    :type dct: dict
    :param dct: dict onto which the merge is executed
    :type merge_dct: dict
    :param merge_dct: dct merged into dct
    """
    for k, v in merge_dct.items():
        if k in dct and isinstance(dct[k], dict) and isinstance(merge_dct[k], collections.Mapping):
            dict_merge(dct[k], merge_dct[k])
        else:
            dct[k] = merge_dct[k]