Cipher machine and bicycle: what they have in common

1. Step 1. Cipher machine — has part — Keyboard. A keyboard.
2. Step 2. Keyboard — is part of — Laptop. The keyboard is built into the laptop's case.
3. Step 3. Laptop — has part — Lithium-ion battery. A battery.
4. Step 4. Lithium-ion battery — is part of — Electric bicycle. A battery.
5. Step 5. Electric bicycle — evolved from — Bicycle. A bicycle with an electric drive.

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