<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _filter_from_dict(current: Dict[str, Any]) -> Dict[str, Any]: """Takes in a nested dictionary as a filter and returns a flattened filter dictionary"""

    filter_ = dict()

    for k, v in current.items():
        if isinstance(v, dict):
            for sub, v2 in _filter_from_dict(v).items():
                filter_[f'{k}.{sub}'] = v2
        else:
            filter_[k] = v

    return filter_