6.8 Functions are objects

• A function is also an object in Python, having a type, identity, and value.
• A function definition like def print_face(): creates a new function object with the name print_face bound to that object.

• A part of the value of a function object is compiled bytecode that represents the statements to be executed by the function

  • A bytecode is a low-level operation, such as adding, subtracting, or loading from memory

  

  The function adds 1 to an argument and returns the result. The corresponding bytecode for the function requires 4 bytecode operations to perform the addition, and 2 to return the result.

• Functions can be passed like any other object as an argument to another function

• Consider the following example, which defines two different functions print_human_head() and print_monkey_head().

  • A third function print_figure() accepts a function as an argument, calling that function to print a head, and then printing a body.