module Boolean
A module with no code within it. Just meant to be included, that’s all.
@example Instance type checking
0.is_a?(Boolean) #=> false nil.is_a?(Boolean) #=> false
@example Class type checking
Object < Boolean #=> nil (false) NilClass < Boolean #=> nil (false) Class < Boolean #=> nil (false)
@see TrueClass
@see FalseClass