Passing functions as arguments

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Accepted Answer

A 'first-class object' is one that can be used anywhere any other value can: passed as an argument, returned from a function, assigned to a variable, or stored in a list or dict. Python functions satisfy all of these, which is what makes higher-order functions like `map`, `sorted(key=...)`, and decorators possible. This is the mental model that makes a lot of Python idioms click - a function is just a value.