message: adds TODO to probe method about adding virtual tip during probe
diff: @@ -12,7 +12,7 @@ X_SWITCH_OFFSET_MM = 5.0
  Y_SWITCH_OFFSET_MM = 2.0
  Z_SWITCH_OFFSET_MM = 5.0
  -Z_PROBE_CLEARANCE_MM = 5.0
  +Z_OFFSET_DURING_PROBE = 5.0
  BOUNCE_DISTANCE_MM = 5.0
  XY_CLEARANCE = 7.5
  @@ -50,10 +50,10 @@ def probe_instrument(instrument, robot) -> Point:
  # Each list item defines axis we are probing for, starting position vector
  # relative to probe top center and travel distance
  hot_spots = [
  - ('x', -rel_x_start, X_SWITCH_OFFSET_MM, Z_PROBE_CLEARANCE_MM, size_x), # NOQA
  - ('x', rel_x_start, X_SWITCH_OFFSET_MM, Z_PROBE_CLEARANCE_MM, -size_x), # NOQA
  - ('y', Y_SWITCH_OFFSET_MM, -rel_y_start, Z_PROBE_CLEARANCE_MM, size_y), # NOQA
  - ('y', Y_SWITCH_OFFSET_MM, rel_y_start, Z_PROBE_CLEARANCE_MM, -size_y), # NOQA
  + ('x', -rel_x_start, X_SWITCH_OFFSET_MM, Z_OFFSET_DURING_PROBE, size_x), # NOQA
  + ('x', rel_x_start, X_SWITCH_OFFSET_MM, Z_OFFSET_DURING_PROBE, -size_x), # NOQA
  + ('y', Y_SWITCH_OFFSET_MM, -rel_y_start, Z_OFFSET_DURING_PROBE, size_y), # NOQA
  + ('y', Y_SWITCH_OFFSET_MM, rel_y_start, Z_OFFSET_DURING_PROBE, -size_y), # NOQA
  ('z', 0.0, Z_SWITCH_OFFSET_MM, rel_z_start, -Z_CROSSOVER_CLEARANCE) # NOQA
  ]
  @@ -68,6 +68,10 @@ def probe_instrument(instrument, robot) -> Point:
  robot.home()
  robot.poses = instrument._move(robot.poses, z=safe_height)
  + # TODO (andy) we physically have a tip attached during probe
  + # so it would seem to make more sense to probe also with a virtual tip
  + # attached to the pipette
  +
  for axis, *probing_vector, distance in hot_spots:
  x, y, z = array(probing_vector) + center
  