.true if the object is an instance of the specified
class, otherwise it
returns .false,
An object is an instance of a class if the object is directly an instance of the
specified class or if
class is in the object's direct or mixin
class inheritance chain. For example:
"abc"~isInstanceOf(.string) --> 1
"abc"~isInstanceOf(.object) --> 1
"abc"~isInstanceOf(.mutablebuffer) --> 0