How to use element programmatically in a custom form

Problem/Motivation

I'm having a hard time finding out how I should use this form element inside of a custom form without documentation. It would be appreciated if someone could help me get started.

Steps to reproduce

grep ' * @FormElement("' -R web/modules/contrib/office_hours/
web/modules/contrib/office_hours/src/Element/OfficeHoursSlot.php: * @FormElement("office_hours_slot")
web/modules/contrib/office_hours/src/Element/OfficeHoursTable.php: * @FormElement("office_hours_table")
web/modules/contrib/office_hours/src/Element/OfficeHoursDatelist.php: * @FormElement("office_hours_datelist")
web/modules/contrib/office_hours/src/Element/OfficeHoursList.php: * @FormElement("office_hours_list")
web/modules/contrib/office_hours/src/Element/OfficeHoursDatetime.php: * @FormElement("office_hours_datetime")

Proposed resolution

- Write documentation on how to correctly build a functional form array for an office_hours element.
And/or
- Provide an actual office_hours element that eases this process.

Remaining tasks

None.

User interface changes

None.

API changes

None.

Data model changes

None.