Change usage of boolean to check delimiter

[richard-muvirimi]

Instead of checking whether the delimiter has already been set, made it part of the line

This is:

• performance & bugfix

Checklist:

• Changes are covered by unit tests
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)

[PowerKiKi]

Please do not mix code style changes with behavior change. Fix the code style with composer fix. And provide a measure of performance improvement for this patch.

[PowerKiKi]

underscore should not be used

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
If this is still an issue for you, please try to help by debugging it further and sharing your results.
Thank you for your contributions.

[oleibman]

Equivalent change was made by PR #1518.