Avoid IndexError when passing an empty string to is_prefixed_with_dollar_sign

[sindrig]

• Tests for the changes have been added

• Docs have been added / updated

• All CI checks are green

• What kind of change does this PR introduce?

As shown by the test, we want to return False for the empty string when checking if it is prefixed with a dollar.

• What is the current behavior?

The function is_prefixed_with_dollar_sign raises IndexError when called with the empty string.

• What is the new behavior (if this is a feature change)?

is_prefixed_with_dollar_sign returns False for the empty string.

[lorenzodb1]

@sindrig thank you for your contribution 😄 could you please merge master into your branch?

[sindrig]

@sindrig thank you for your contribution 😄 could you please merge master into your branch?

Done ✔️

[lorenzodb1]

@sindrig thank you for that! Looks like one of the pre-commit checks is failing. Please, run make test and then push the changes

[sindrig]

@sindrig thank you for that! Looks like one of the pre-commit checks is failing. Please, run make test and then push the changes

Import order got mixed up. Fixed ✅

[lorenzodb1]

@sindrig Thank you for your contribution! I went ahead and merged your changes. Really appreciate your work and hope to see another PR of yours soon 😄