fails:Kernel#remove_instance_variable is a public method
fails:Kernel#remove_instance_variable raises a TypeError if passed an Object not defining #to_str
fails:Kernel#remove_instance_variable when passed a String returns the instance variable's value
fails:Kernel#remove_instance_variable when passed a String removes the instance variable
fails:Kernel#remove_instance_variable when passed a Symbol returns the instance variable's value
fails:Kernel#remove_instance_variable when passed a Symbol removes the instance variable
fails:Kernel#remove_instance_variable when passed an Object calls #to_str to convert the argument
fails:Kernel#remove_instance_variable raises a NameError if the instance variable is not defined
fails:Kernel#remove_instance_variable raises a NameError if the argument is not a valid instance variable name
