> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sourcery.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Replace For Index with Underscore

#### Sourcery refactoring id: `for-index-underscore`

#### Description:

Replaces an unused index in a `for` loop or comprehension with an underscore

#### Before:

```python
for hat in my_wardrobe.hats:
    shout("Hurrah!")
```

```python
shouts = [shout("Hurrah!") for hat in my_wardrobe.hats]
```

#### After:

```python
for _ in my_wardrobe.hats:
    shout("Hurrah!")
```

```python
shouts = [shout("Hurrah!") for _ in my_wardrobe.hats]
```

#### Explanation:

Sometimes in a for loop or comprehension we just want some code to run a certain
number of times, and don't actually make use of the index variable.

In the above example we have introduced a new variable, `hat`, which we have to
note when reading the code, but actually we don't need it and could replace it
with `_`:

It is a convention in Python to use `_` as a throwaway name for unused
variables. This means your brain can learn to safely ignore these, reducing the
overhead to understand the code. Where you see this in a `for` loop or
comprehension it is immediately clear that the loop is just used to repeat a
block of code and we don't care about the value being iterated over.