Department of Computer Science, Stanford University, Stanford, CA, USA. mcclosky@stanford.edu|Department of Computer Science, Stanford University, Stanford, CA, USA. mcclosky@stanford.edu|Department of Computer Science, Stanford University, Stanford, CA, USA. mcclosky@stanford.edu|Department of Computer Science, Stanford University, Stanford, CA, USA. mcclosky@stanford.edu|Department of Computer Science, Stanford University, Stanford, CA, USA. mcclosky@stanford.edu