In the following Python code, what is the purpose of the def keyword?

def my$\_$function$($x$)$:

$$return x $*2$

y $=$ my$\_$function$(5)$

In the following Python code, what is the purpose of the def keyword?

def my$\_$function$($x$)$:

$$return x $*2$

y $=$ my$\_$function$(5)$

To classify y as an expression.

To define a new function.

To return a value from the function.

To classify x as a variable.