# Writing functions in Python

Functions are an essential part of programming, as they can execute a block of code at once.
Often it's an excellent way to re-use blocks of code.

Let's give it a go and see how they work in Python.

## Creating a function in Python

A function is made by prefixing the `def` keyword.

```python
def foo():
	print("Bar")
```

However, running our code now will not do anything since we didn't call our function yet.

## Executing the function

To run/execute the function, we must call it somewhere in our code. In general, this happens when a specific criterion is matched, but let's just run it as is.

```python
def foo():
	print("Bar")

foo()
```

When we run our code now, it returns `Bar`

## Passing and returning data

Having a function that prints out something is not convenient so let's see how we can give it data and return something.

Let's say we want to make a function that multiplies a number by itself and returns the output.

Meaning, if we put in the number 5, it should run `5x5` and return `25`.

```python
def multiply(number):
    return number * number

print(multiply(5))
```

Running this code will indeed return `25`.

We can easily have the function accept multiple arguments like so:

```python
def multiply(number, multiplier):
    return number * multiplier

print(multiply(5, 10))
```

This will return `50`.

And one cool thing we can do is send the arguments based on their key value like this.

```python
multiply(number=5, multiplier=2)
```

You might not know how many arguments you're expecting in some cases, and you can prepend the argument with an asterisk (\*).

```python
def feed_animals(*animals):
    print(animals)
    print(animals[1])

feed_animals('Cow', 'Chicken', 'Goat')
```

Which will return:

```text
('Cow', 'Chicken', 'Goat')
Goat
```

There are some more additions to functions, but this covers the basics for Python functions.

### Thank you for reading, and let's connect!

Thank you for reading my blog. Feel free to subscribe to my email newsletter and connect on [Facebook](https://www.facebook.com/DailyDevTipsBlog) or [Twitter](https://twitter.com/DailyDevTips1)