text: from physicsTable import *
  import sys
  
  if __name__ == '__main__':
      assert len(sys.argv) == 3, "Must provide two names -- to reverse and new file"
      tr = loadTrial(sys.argv[1])
      b = tr.ball
      tr.ball = (b[0], (-b[1][0], -b[1][1]), b[2], b[3], b[4])
      tr.save(sys.argv[2], askoverwrite = True)