The name is a legacy from when such slots were the unmarked case in Kernel-E (that is, the pattern "foo" created a SimpleSlot).
You can obtain a read-only facet on a SimpleSlot via Slot#readOnly/0.
Returns the SimpleSlot guard, which all products of this maker pass.
run(value :any) :SimpleSlot
Makes a SimpleSlot with the specified initial value.
SimpleSlots have no protocol beyond Slot.