Filtering a dictionary recursively

filterdict.py

#!/usr/bin/env python3

"""Filter None out of a dictionary with nested data structures."""

from typing import Dict


def filterdict(dirty: Dict) -> Dict:
    """Filter `None` values out of a dictionary.

    Args:
        dirty (Dict): Dictionary with None values present.

    Returns:
        Dict: Dictionary with None values removed.
    """
    clean = {}
    for k, v in dirty.items():
        if v is not None:
            if isinstance(v, dict):
                clean.update({k: filterdict(v)})
            elif isinstance(v, list):
                placeholder = []
                for i in v:
                    if i is not None:
                        if isinstance(i, dict):
                            placeholder.append(filterdict(i))
                        else:
                            placeholder.append(i)

                clean.update({k: placeholder})
            else:
                clean.update({k: v})

    return clean