class REXML::Child

def initialize( parent = nil )

supplied value, and self will be added to the parent
if supplied, the parent of this child will be set to the
parent::
sure this method is called.
Constructor. Any inheritors of this class should call super to make 
def initialize( parent = nil )
  @parent = nil
  # Declare @parent, but don't define it.  The next line sets the
  # parent.
  parent.add( self ) if parent
end