how to iterate keys independently from the for loop in python code example

Example 1: python loop through dictionary

d = {'x': 1, 'y': 2, 'z': 3} 
for key in d:
    print key, 'corresponds to', d[key]

Example 2: how to iterate over dictionary in python

>>> for key, value in a_dict.items():
...     print(key, '->', value)
...
color -> blue
fruit -> apple
pet -> dog