Using a dict to discard repeated items in a list of tuples

gistfile1.py

>>> a = [(1, 'red'), (2, 'red'), (1, 'blue'), (3, 'green')]
>>> b = dict(a)
>>> b
{1: 'blue', 2: 'red', 3: 'green'}
>>> 
# keep in mind 2d occurrence of the key will be the one remaining in the dict