python - Manipulating deep values of a dictionary -

i go from

first =  {'a' :      {'b' :         {'c' : ['d', 'e'],          'f' : ['g']         }     } } 

to

z = 0 second =  {'a' :      {'b' :         {'c' :              {'d' : z,               'e' : z              },          'f' :             {'g' : z}         }     } } 

i'm looking pythonic way this. want change every 3rd level elements of first (c , f) list dictionary keys elements of list (d, e example).

>>> {k1: {k2: {k3: {k4:0 k4 in v3} k3, v3 in v2.items()} k2, v2 in v1.items()} k1, v1 in first.items()} {'a': {'b': {'c': {'e': 0, 'd': 0}, 'f': {'g': 0}}}} 

=)

(if don't want shot in code review, stick advice 9000 in comments, please. i.e. third level dicts , manipulate directly.)