Exercise for reference: 

Create a dictionary of keys a, b, c where each key has as value a list from 1 to 10, 11 to 20, and 21 to 30, respectively. Then print out the dictionary in a nice format.

Answer: 

from pprint import pprint

d = {"a":list(range(1, 11)), "b":list(range(11, 21)), "c":list(range(21, 31))}
pprint(d)

Explanation: 

We're using ranges here to construct the lists. We're also using the built-in Python pprint  module, which is used to print out well-formatted views of datatypes in Python.