Solve the programming task below in a Python markdown code block.
# Covfefe


Your are given a string. You must replace the word(s) `coverage` by `covfefe`, however, if you don't find the word `coverage` in the string, you must add `covfefe` at the end of the string with a leading space.

For the languages where the string is not immutable (such as ruby), don't modify the given string, otherwise this will break the test cases.
Also feel free to reuse/extend the following starter code:
```python
def covfefe(s):
```