Adds a new assertion function to the Assert "class" (function).
The name of the function to add.
The definition of the function to add, this can be a string (is.object),
an array of strings (["is", "obejct"]) which identify the sequence of operations to perform
or a IScopeFn function, or an IAssertClassDef object.
OptionalresponseHandler: (result: any) => anyAssertionError - If the definition is invalid.
Export the functions (and global
assert)