Mutant::Meta::Example.add do source '/foo/' singleton_mutations mutation '//' # match all mutation '/a\A/' # match nothing end Mutant::Meta::Example.add do source '/#{foo.bar}n/' singleton_mutations mutation '//' # match all mutation '/#{foo}n/' mutation '/a\A/' # match nothing mutation '/#{self.bar}n/' mutation '/#{nil}n/' mutation '/#{self}n/' end