Python dict deep merge

deep_merge.py

from copy import deepcopy
from functools import reduce


def deep_merge(*dicts, update=False):
    """
    Merges dicts deeply.

    Parameters
    ----------
    dicts : list[dict]
        List of dicts.
    update : bool
        Whether to update the first dict or create a new dict.

    Returns
    -------
    merged : dict
        Merged dict.
    """
    def merge_into(d1, d2):
        for key in d2:
            if key not in d1 or not isinstance(d1[key], dict):
                d1[key] = deepcopy(d2[key])
            else:
                d1[key] = merge_into(d1[key], d2[key])
        return d1

    if update:
        return reduce(merge_into, dicts[1:], dicts[0])
    else:
        return reduce(merge_into, dicts, {})