Shower head and pneumatic tube: what they have in common

1. Step 1. Shower head — is part of — Shower. A sprayer.
2. Step 2. Shower — uses — Water heater. Hot water.
3. Step 3. Water heater — has part — Thermostat. A thermostat.
4. Step 4. Thermostat — is part of — Refrigerator. A thermostat.
5. Step 5. Refrigerator — has part — Compressor. A compressor with an electric motor.
6. Step 6. Compressor — is part of — Pneumatic tube. A pressure or vacuum blower.

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