How to define constructors for classes defined using define-simple-class

[S D <s dot mailinglists at gmail dot com>]

I know there is a way to use init-keyword: which sort of provides a
mechanism to specify additional arguments to make which as per the
documentation are set using the set-slot! after the object is created.
But if I want to write a class using define-simple-class that inherits
a class with no default constructor, then I have to similarly define a
constructor which takes arguments and pass them to the parent class's
constructor.