In [1]: d = {'x':1, 'y':2, 'z':3}

In [2]: for key in d:
  ...:   print key, 'corresponds to', d[key]
  ...: 
y corresponds to 2
x corresponds to 1
z corresponds to 3

In [4]: for key, value in d.items():
  ...:   print key, 'corresponds to', value
  ...: 
y corresponds to 2
x corresponds to 1
z corresponds to 3