### فهرست عناوین

12. حلقه‌های for

#### موضوع بعدی

14. Argument par défaut

# 13. Function arguments¶

We have seen that, when there are more than one type of objects in Reeborg's World, we must sometimes specify which object Reeborg must take or put down by using a function argument as in:

```take("token")
put("star")
```

However, we have not seen yet how to define such a function. It is actually fairly easy: all we have to do is include a variable as an argument between the parentheses when defining the function. For example, suppose we want to define a function `turn()` that would take a number as its argument so that the number indicates the number of left turn we want Reeborg to make. Thus `turn(1)` would correspond to a single left turn whereas `turn(3)` would correspond to three left turns (which, as we know, amounts to having Reeborg make a right turn). One way to do this is as follows:

```def turn(number):
for _ in range(number):
turn_left()
```

Define such a `turn` function and try it out in a program.

## 13.1. Many arguments¶

If you recall, `print()` can take more than one argument, with each argument separated by a comma. You can probably guess how we can define a similar function:

```def my_function(argument_1, argument_2, ...):
# code block
```

Suppose that, like above, we want to be able to specify a number of turns ... and also a number of moves ... and a number of whatever. We could define a function like `turn` for each type of repeated action; however, there is a more general way which only requires to define a single function, which we will call my_repeat (repeat would have been a better name, but it's a special Reeborg keyword). Here's a possible definition:

```def my_repeat(function, number):
for _ in range(number):
function()
```

So, if we call it with `turn_left` and `3` as arguments:

```my_repeat(turn_left, 3)
```

it will be interpreted as:

```for _ in range(3):   # number is replaced by 3
turn_left()      # function is replaced by turn_left
```

which we recognize as our familiar `turn_right` equivalent. However, having defined `my_repeat` we can use it with different numbers and functions, such as:

```my_repeat(move, 4)   # move 4 steps
```

Define such a `my_repeat` function and try it out in a program.
Unlike `print()`, which can take an arbitrary number of arguments, the functions we have defined so far will always require a set number of arguments (1 for `turn`, 2 for `my_repeat`). You should check what happens if you give a different number of arguments than what was indicated when defining the function.