How to import a custom python module file into azure function

How to import a custom python module file into azure function.
My python class needs to import my custom class. For instance

```
import os
import time
from optparse import OptionParser
**from mlutil import HTMLPath**
```
How can I upload/where to upload my **mlutil.py** file so that my import from mlutil class won't throw error in my azure function ?

