Constructor Messages 

  Constructor messages are used to create new instances of a class. The
  default constructor message, new(), is implemented by Class(y) and
  inherited by all classes.

  When a constructor message is sent to a class object, Class(y) creates a
  new, empty object of that class and sends the init() message to it, to
  initialize it. The init method is referred to as an initializer
  method, and is discussed in the next section.

  All arguments passed to the constructor are passed in turn to the init
  method to allow it to initialize the object correctly.

  When the initializer method returns, the constructor returns the new
  object to the caller. It is thus not necessary for the initializer method
  to return a value, although by convention, methods which do not return a
  value return self.

  It is possible to define constructors other than new(). This can be
  useful when there is more than one way to initialize the objects of a
  class. For more information, see the section Alternate Constructors.