Question

Look at the following function definition: def do_something(number): return number * 2 a. What is the name of the function? b. What does the function do? c. Given the function definition, what will the following statement display? print(do_something(10))

Short answer

```python def do_something(number): return number * 2 ``` Answer: The output of the statement will be 20.

Step-by-step solution

Find the function name

In the given code, a function is defined using the "def" keyword. The name of the function comes immediately after the "def" keyword. In this case, the name of the function is "do_something".

Analyze the function

Now that we have identified the name of the function, let's understand what it does. The function takes a single input called "number" and it returns the result of multiplying "number" by 2. This function essentially doubles the input value.

Find the output of the function with the given input

Using the function definition, we can determine the output of the given statement: "print(do_something(10))". Since "do_something" doubles its input, when we pass the value 10 to the function, the result will be 10 * 2 which equals 20. Therefore, the statement will display the number 20.

Key concepts

Function Definition

In Python, defining a function is like teaching the computer to perform a specific task, just like a set of instructions. The process starts with the "def" keyword followed by the function name, and finally a pair of parentheses. These parentheses might hold some input variables, which enable us to provide specific data the function will work with. After the function definition line, there should be a colon (:) at the end, indicating that the indented lines that follow make up the body of the function.

Let's break down the function definition in the exercise: `def do_something(number):`

• `def`: This is the keyword used to start function definitions.
• `do_something`: This is the name of the function.
• `number`: This is a variable inside the parentheses, known as a parameter, which the function uses to perform its operation.

In essence, a function definition is like a blueprint. Once defined, you can "call" or "invoke" this function from anywhere in your code, and it will perform its task whenever needed.

Return Statement

A function in Python can perform its task and then send back a result using the `return` statement. This idea is similar to delivering a completed assignment back to you after working on it. Inside the function, the `return` keyword determines what value will be sent back to the place where the function was called. In the given function, there is a specific `return` statement: `return number * 2`. As a result, whatever data was given to the function as input will be processed, and the result of `number * 2` will be sent back as the final output.

Here’s how the process works:

• The function receives an input, specifically a number.
• It processes this input by multiplying it by 2.
• The `return` statement then provides this result back to the caller of the function.

Remember that once a `return` statement is executed, the function ends its execution. If there are lines of code after a `return`, they will not be executed. Therefore, drafting your `return` statements properly is crucial for the accurate functioning of your program.

Function Input and Output

The heart of any function's interaction lies in its input and output. The function inputs are called parameters, and they appear within the parentheses during function definition. These are essentially placeholders for the actual values that you will provide when calling the function.

In our example, `number` is a parameter. When using the function with code like `do_something(10)`, the number 10 is the input value that replaces the `number` parameter.

On the flip side, a function's output is the result it sends back via the `return` statement. Outputs answer these critical questions:

• What did the function do with the inputs?
• What should be given back for further use in the code?

For instance, in `print(do_something(10))`, we are calling the function with 10 as input, and expect it to return 20 as output. The `print` function then displays this output. Function input and outputs are like the asking and answering of questions within your code, forming the base of powerful problem-solving techniques in Python.