http://docs.python.org/2/reference/expressions.html#evaluation-order
says that the dicts are evaluated in this order:
  {expr1: expr2, expr3: expr4}

however each value is evaluated before the respective key:
def f(x):
  print(x)
  return x

{f('k1'): f('v1'), f('k2'): f('v2')}

v1
k1
v2
k2
{'k1': 'v1', 'k2': 'v2'}