throwing shadows on your saxophone

My favourite busker - but I love the saxophone (to listen to, can't play any instrument - or sing). A large crowd (predominately of women) had gathered to hear him do a fabulous instrumental version of Fields of Gold.

Today I took the car into the garage because a warning light had appeared on the dashboard - the computer said oxygen sensor.
I asked if the car thought it was at a high altitude - the head of the service department explained to me (in great detail) what the oxygen sensor does. (I already knew this but decided not to explain the altitude thing was a joke).
A new oxygen sensor was fitted (taking a number of hours - hence the trip into town and spotting the busker).
As I drove away from the garage the same warning light appeared on the dashboard.
I returned to the garage - the computer said oxygen sensor.
The mechanic said a few choice words.
The car is apparently safe to drive and I'm returning it to them in a few weeks for the whole day when they will investigate why the light is on and why the computer says oxygen sensor.
They'll probably remove the bulb in the warning light.
Ho hum!