Why dict.get(key) instead of dict[key]?

Question

Today, I came across the dict method get which, given a key in the dictionary, returns the associated value.

For what purpose is this funct

Answer 1

A gotcha to be aware of when using .get():

If the dictionary contains the key used in the call to .get() and its value is None, the .get() method will return None even if a default value is supplied.

For example, the following returns None, not 'alt_value' as may be expected:

d = {'key': None}
assert None is d.get('key', 'alt_value')

.get()'s second value is only returned if the key supplied is NOT in the dictionary, not if the return value of that call is None.