(flo val)
  val: any type
  returns a flo

Converts its argument to a floating-point number.

• If the argument is already a floating-point number, it's returned.

• If the argument is an integer, it's converted to floating-point. Integers with an absolute value up to 2 ^ 24 are represented exactly. Other integers may be rounded - the rounding strategy is unspecified.

• If the argument is a character, it's converted to an integer, then converted to a floating-point number as above.

• If the argument is a boolean, returns 0.0 for #f or 1.0 for #t.

• Any other argument is an error.