A plumber comes over to repair a broken water heater. He looks at it, taps a pipe with his wrench, and it's fixed. He hands the customer a bill for $500. The customer becomes angry because all the plumber did was tap a pipe, and demands to see an itemized bill.
A plumber comes over to repair a broken water heater. He looks at it, taps a pipe with his wrench, and it's fixed. He hands the customer a bill for $500. The customer becomes angry because all the plumber did was tap a pipe, and demands to see an itemized bill.
The plumber dutifully provides the bill:
* Pipe tapping: $5
* Knowing where to tap: $495