UNIVERSAL is base class for ALL classes in Object Oriented Perl. UNIVERSAL::isa (isa stands for "is a") is method which can tell You if object is blessed in package or inherits from package. . This module overloads UNIVERSAL::isa with a version that makes sure that, when called as a function on objects which override isa, isa will call the appropriate method on those objects . In all other cases, the real UNIVERSAL::isa gets called directly.
