fails:Float#<=> returns -1, 0, 1 when self is less than, equal, or greater than other
fails:Float#<=> returns nil when either argument is NaN
fails:Float#<=> returns nil when the given argument is not a Float
fails:Float#<=> returns 1 when self is Infinity and other is a Bignum
fails:Float#<=> returns -1 when self is negative and other is Infinty
fails:Float#<=> returns -1 when self is -Infinity and other is negative
fails:Float#<=> returns 1 when self is negative and other is -Infinity
