fails:Kernel.String raises a TypeError if #to_s does not exist
fails:Kernel.String raises a TypeError if respond_to? returns false for #to_s
fails:Kernel.String raises a TypeError if #to_s is not defined, even though #respond_to?(:to_s) returns true
fails:Kernel.String calls #to_s if #respond_to?(:to_s) returns true
fails:Kernel.String raises a TypeError if #to_s does not return a String
fails:Kernel#String raises a TypeError if #to_s does not exist
fails:Kernel#String raises a TypeError if respond_to? returns false for #to_s
fails:Kernel#String raises a TypeError if #to_s is not defined, even though #respond_to?(:to_s) returns true
fails:Kernel#String calls #to_s if #respond_to?(:to_s) returns true
fails:Kernel#String raises a TypeError if #to_s does not return a String
