Define default dictionary values and handle missing keys.

Signatures:

None

Examples:

# If key exists, then return value. Else return the default value
name = cowboy.get('name', 'The Man with No Name')

# If key exists, then return value. Else set cowboy['name'] to 'The Man with No Name'
# and return the value
name = cowboy.setdefault('name', 'The Man with No Name')

# Handle missing keys with defaultdict
from collections import defaultdict

student_grades = defaultdict(list)
grades = [
    ('elliot', 91),
    ('neelam', 98),
    ('bianca', 81),
    ('elliot', 88),
    ]

for name, grade in grades:
    student_grades[name].append(grade)

print(student_grades)
# output: defaultdict(<class 'list'>, {'neelam': [98], 'bianca': [81], 'elliot': [91, 88]})

References:

1. Python Interview Tips - Define Default Values in Dictionaries
2. Python Interview Tips - Handle Missing Keys