is_universal#
Report whether $class is UNIVERSAL itself or one of its ancestors via @ISA.
Synopsis#
if (mro::is_universal($class)) { … }
Returns a true value exactly when every class in the program can inherit methods from $class. That happens in two cases: the class literally is UNIVERSAL, or something has pushed it into @UNIVERSAL::ISA (directly or indirectly). Most programs never see the second case, but frameworks that mix a trait into UNIVERSAL rely on it.
A single argument is required; calling with any other arity croaks with Usage: mro::is_universal(classname).