Perhaps you should try some spelling variations:
vpython collisions » vpython colisoes (Expand search), proton collisions (Expand search), photon collisions (Expand search)
based programming » and programming (Expand search), based program (Expand search), cone programming (Expand search)
collisions python » collisions within (Expand search), collisions with (Expand search), collisions on (Expand search)
decrease based » decreased base (Expand search), decrease blood (Expand search)
python python » pythons python (Expand search), piton python (Expand search), pitons python (Expand search)
decrease to » decreased to (Expand search), decrease toc (Expand search), decrease the (Expand search)

You may be able to get more results by adjusting your search query.

• Removing quotes may allow a broader search: (( decrease to decrease based programming ) OR ( vpython collisions python python programming ))~.