Assignment

HW 1: Writing Some Rust

Implement the command-line gcd example of Chapter 2 of the course text. Rename it as calc. Modify it to apply different functions depending on the first argument passed to it. Functions to be implemented:

"sum": The sum of the remaining arguments.
```
  $ target/debug/calc sum 1 2 3
  6
```
"product": The product of the remaining arguments.
```
  $ target/debug/calc product 1 2 3
  6
```
"gcd": The Greatest Common Divisor of the remaining arguments.
```
  $ target/debug/calc gcd 10 14 12
  2
```
"lcm": The Least Common Multiple of the remaining arguments.
```
  $ target/debug/calc lcm 10 14 12
  420
```

When no arguments beyond the function are given, calc should silently exit with success.

      $ target/debug/calc lcm
      $ echo $?
      0

When one argument beyond the function is given, calc should display that argument and exit with success.

      $ target/debug/calc lcm 12
      12

Your calc implementation should contain adequate tests and assertions. It should be formatted according to the official Rust formatting style.

Please submit a ZIP archive containing your source files only: no target/ directory or .git directory. Your submission should contain a README.md file in Markdown format giving a writeup of what you did, how it went, and how you tested it.