"Sander Land" <sander.land / gmail.com> writes:

>> On 2/19/06, George Ogata <g_ogata / optushome.com.au> wrote:
>> ...
>> define_method("#{arg}?"){|| !send(arg).nil?}
>> ...
> what about send(arg) == false ?

Good point!  The koans didn't question that, though.

Indeed, `!!send(arg)' is a better solution.  So is using `defined?'
instead of `instance_variables.include?'.