Solve the programming task below in a Python markdown code block.
The code provided is supposed replace all the dots `.` in the specified String `str` with dashes `-`

But it's not working properly.

# Task

Fix the bug so we can all go home early.

# Notes

String `str` will never be null.
Also feel free to reuse/extend the following starter code:
```python
def replace_dots(str):
```