Department of Computer Science, Tufts University, Medford, MA 02155, USA. fox.andrew.d@gmail.com|Department of Computer Science, Tufts University, Medford, MA 02155, USA. fox.andrew.d@gmail.com|Department of Computer Science, Tufts University, Medford, MA 02155, USA. fox.andrew.d@gmail.com|Department of Computer Science, Tufts University, Medford, MA 02155, USA. fox.andrew.d@gmail.com