function self = push(self,data)
%PUT Put data in the queue 
%   queue = put(queue,data)
%
% $Id$

if isempty(data)
  return
end

if isequal(data, self.data)
  return
end

self.index = self.index+1;
self.lifo(end+1,:) = data; 
self.data = data;
