;'<<SPEC'
### `number?` ###
-> Tests for functionality "Evaluate Robin Expression (with literal)"
`number?` evaluates its argument, then evaluates to `#t` if it is a
number, `#f` otherwise.
| (number? 7)
= #t
| (number? 0)
= #t
| (number? ())
= #f
| (number? #t)
= #f
| (number? (literal seven))
= #f
That's a good question...
| (number? (literal 7))
= #t
The argument to `number?` may (naturally) be any type, but there must be
exactly one argument.
| (number? 6 4)
? abort (illegal-arguments (6 4))
| (number?)
? abort (illegal-arguments ())
'<<SPEC'
(require number?)