dict_example

>>> a = dict()
>>> a == {}
True
>>> a[1] = 'value 1'
>>> a['2'] = 2
>>> a[(3, 3)] = (3, 3)
>>> a[None] = 4
>>> a
{1: 'value 1', '2': 2, (3, 3): (3, 3), None: 4}
>>> del a[3, 3]
>>> a
{1: 'value 1', '2': 2, None: 4}
>>> a.setdefault('key', 'default')
'default'
>>> a
{1: 'value 1', '2': 2, None: 4, 'key': 'default'}
>>> a.setdefault('key', 'new_default')
'default'
>>> a
{1: 'value 1', '2': 2, None: 4, 'key': 'default'}
>>> '2' in a
True
>>> for key in a:
...     print(key)
...
1
2
None
key
>>> for key, value in a.items():
...     print(key, value)
...
1 value 1
2 2
None 4
key default
>>> for value in a.values():
...     print(value)
...
value 1
2
4
default

>>> b = {i:i**2 for i in range(10)}
>>> b
{0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}