Python - Check if an exact list item exists in a string

Question

I'm trying to match a string exactly in another string.

'-w'

And I have a few different string target formats below.

`string -w`
`string -wy`
`string -w string`
`string -wy string`

I've tried the basic check but it matches all of the above four strings, expected:

`if "-w" in string`

I've a tried regex pattern like below but it matches one of the above strings, again expected.

`-ks\s`

The expected outcome would be for -w to only be found in the below two strings.

`string -w`
`string -w string`

Any help greatly appreciated.