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Introduction to Functions
Returns

So far, we have only seen functions that print out some result to the console. Functions can also return a value to the user so that this value can be modified or used later. When there is a result from a function that can be stored in a variable, it is called a returned function value. We use the keyword `return` to do this.

Here’s an example of a function `divide_by_four` that takes an integer argument, divides it by four, and `return`s the result:

``````def divide_by_four(input_number):
return input_number/4``````

The program that calls `divide_by_four` can then use the result later:

``````result = divide_by_four(16)
# result now holds 4
print("16 divided by 4 is " + str(result) + "!")
result2 = divide_by_four(result)
print(str(result) + " divided by 4 is " + str(result2) + "!")``````

This would print out:

``````16 divided by 4 is 4!
4 divided by 4 is 1!``````

In this example, we returned a number, but we could also return a String:

``````def create_special_string(special_item):
return "Our special is " + special_item + "."

special_string = create_special_string("banana yogurt")

print(special_string)``````
``Our special is banana yogurt.``

### Instructions

1.

The function `calculate_age` in script.py creates a variable called `age` that is the difference between the current year, and a birth year, both of which are inputs of the function. Add a line to return `age`.

2.

Outside of the function, call `calculate_age` with values `2049` (`current_year`) and `1993` (`birth_year`) and save the value to a variable called `my_age`.

3.

Call `calculate_age` with values `2049` (`current_year`) and `1953` (`birth_year`) and save the value to a variable called `dads_age`.

Print the string `"I am X years old and my dad is Y years old"` to the console, with `my_age` where the `X` is and `dads_age` where the `Y` is.