Dictionaries with default values.
""" approaches 1 & 2 work on the standard dic"""
# approach 1: via dict.get()
dict default
dict.get('key', 'default') # fallback insted of KeyError handling
# approach 2: via setdefault()
dict default
default.setdefault('my default value')
# approach 3: via defaultdic
from collections import defaultdict
ice_cream = defaultdict(lambda: 'default_value')