message: feat: Add an intregrated man page to the math builtin
diff: @@ -9,6 +9,22 @@ const REPL_GUIDE: &str = r#"Ion's integrated calculator
  Type in expressions to have them evaluated.
  Type "help" for help."#;
  +const REPL_HELP: &str = r#"
  +Ion-math is a floating-point calculator
  +You can use infix (ex: 1 + 2 * 3) or polish (+ * 2 3 1) notations.
  +Non-operator, non-number sequences will be treated as variables for interpolation.
  +
  +Examples:
  + $ 1 + 3-2
  + >> 2
  + $ 0.00001 + 0.0001
  + >> 0.00011
  +
  + In Ion if $a = 2, $b = 3, $c = 7
  + $ a * b * c
  + >> 42
  +"#;
  +
  fn calc_or_polish_calc(args: &str) -> Result<Value, CalcError> {
  match eval(args) {
  Ok(t) => Ok(t),
  @@ -73,6 +89,7 @@ pub fn math(args: &[crate::types::Str], _: &mut crate::Shell<'_>) -> Status {
  {
  Ok("") => return Status::SUCCESS,
  Ok(text) if text.trim() == "exit" => return Status::SUCCESS,
  + Ok(text) if text.trim() == "help" => eprintln!("{}", REPL_HELP),
  Ok(s) => {
  let result = calc_or_polish_calc(s);
  match result {
  