I want to match every week day in a string where all words are comma separated.

Examples:
"mon, thu, fry" should be matched
"mon, tue, sat" should be matched
"" should not be matched
"mon, tue, wed, thu, fri, sat, sun" should be matched
"foo, bar" should not be matched

I came up with this regex but it matches only the string containing ALL week days:

```
^(mon|tue|wed|thu|fri|sat|sun)$

```

How can I match them "indipendently"?

I am using python3