A mix-in for classes allowing relational operations. Classes including this module must define the basic relational operators <=>. All other relational operators can be derived through use of those definitions.
Returns true if self and other are equal.
Returns nil if <=> returns nil.
Returns true if self is greater than other.
If <=> returns nil, throws an ArgumentError exception.
Returns true if self is greater than or equal to other.
If <=> returns nil, throws an ArgumentError exception.
Returns true if self is less than other.
If <=> returns nil, throws an ArgumentError exception.
Returns true if self is less than or equal to other.
If <=> returns nil, throws an ArgumentError exception.
Returns true if self falls within a range from min to max, inclusive.
If self <=> min or self <=> max returns nil, throws an ArgumentError exception.