Added isName function and added '$' to test

[sampaioletti]

Fixes #118

[rohitkeshwani07]

I have a similar use case but don't u think it should be configurable?

[sampaioletti]

Sure I think thats an idea, are you thinking ability to pass in whatever runes you would like or just ability to enable/disable '$'

[rohitkeshwani07]

Whatever is between [ and ] is treated as variable right now. What if these 2 can be configured??

Prefix and Suffix to find the variable?

For our usecase it will be $ and space