[1
] a BFH Educational Consultants , Seattle , WA , 98119 , USA
[2
] b Department of Information & Computer Science , Metropolitan State University
, Saint Paul , MN , 55106 , USA
[3
] c Department of Computer Science , College of Charleston , Charleston , SC , 29424
, USA
[4
] d Department of Computer Science & Computer Engineering , Pacific Lutheran University
, Tacoma , WA , 98447 , USA
[5
] e Department of Computing and Software Systems , University of Washington Bothell
, Bothell , WA , 98011 , USA