Rebuilding simple programs into multi-function programs

1. Rebuild the solution to 2.21 (page 98)
   • Rebuild the “work” as a separate function.
   • Rebuild the input as a separate function.
   • Rebuild the output as a separate function.
2. Rebuild the solution to 3.27 (page 145)
   • Rebuild the “work” as a separate function.
   • Rebuild the output as a separate function.
   • Rebuild the input as a separate function.
3. Rebuild the solution to 3.29 (page 145)
   • Rebuild the “work” as a separate function.
   • Rebuild the input as a separate function.
   • Rebuild the output as a separate function.