Constructor Messages and Methods
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    Constructors messages are used to create new instances of a class.  A
    constructor method is declared in the class declaration with a
    statement of the following form:

        METHOD <methodName> CONSTRUCTOR
    or:
        METHOD <methodName> CTOR                    // abbreviated form

    When a constructor message is sent to a class object, before invoking
    the code of the associated constructor method, a new instance of that
    class is created by the Class(y) kernel.  Once this has been done, the
    constructor method behaves like a normal method in that it has a self
    which is an instance of a class.  Once the method's code has been
    executed, a reference to self is returned to the caller.  This is
    done automatically by the Class(y) kernel - the method code itself
    should just perform a simple RETURN.

    When writing the code for a constructor, if the class has a superclass,
    it is necessary to invoke the superclass' constructor to perform
    initialization of the part of the object which belongs to the
    superclass.  Class(y) provides an automatic mechanism for doing this.
    The definition of a constructor allows a second parameter list to be
    included, which is passed up to the superclass constructor before
    executing the method code.

    The CONSTRUCTOR method definition command is used to assist with
    this automatic chaining of superclass constructors.  See the entry for
    the CONSTRUCTOR command for more details.