(left, right)
return left
Merges one internal groupby dictionary (right) into another one (left) and returns
    the merging result. Used for aggregating partial dicts into single result.
Merges one internal groupby dictionary (right) into another one (left) and returns
    the merging result. Used for aggregating partial dicts into single result.
Merges one internal groupby dictionary ( right ) into another one ( left ) and returns the merging result . Used for aggregating partial dicts into single result .
def merge_groupby_dicts_inplace(left, right):
    """ Merges one internal groupby dictionary (right) into another one (left) and returns
    the merging result. Used for aggregating partial dicts into single result. """

    if not right:
        return left

    for key, right_group_list in right.items():
        left_group_list = left.get(key)
        if left_group_list is None:
            left[key] = right_group_list
        else:
            left_group_list.extend(right_group_list)

    return left
def merge_groupby_dicts_inplace ( left , right ) : if not right : return left for key , right_group_list in right . items ( ) : left_group_list = left . get ( key ) if left_group_list is None : left [ key ] = right_group_list else : left_group_list . extend ( right_group_list ) return left