Python Nested Dictionaries Traversal Search

traversal.py

def df_traversal(d):
    """
    depth-first traversal for dict d
    pre-order method
    ref: http://en.wikipedia.org/wiki/Tree_traversal
    ref: http://en.wikipedia.org/wiki/Depth-first_search
    """

    for key in d:
        print key
        if type(d[key]) == dict:
            df_traversal(d[key])