I thought I was actually going to enter my first RubyQuiz, but I've 
spent three times as much time trying to get Ruby to stop surprising me 
as I have trying to implement my algorithm, and I've had to abandon my 
effort since I don't have the time to spend. Sigh.

Can somebody explain to me how I'm supposed to delete a *single* 
element from an array based on equivalence with an object? and get back 
said array with said element deleted?

In other words....

ar = [1, 2, 3, 8, 15, 15, 8]

ar.delete_one_element!(15)
=> [1, 2, 3, 8, 15, 8]

ar.delete_one_element!(14)
=> [1, 2, 3, 8, 15, 15, 8]

ar.delete_one_element!(nil)
=> [1, 2, 3, 8, 15, 15, 8]

I did find so many different ways of not doing this....

Too enthusiastic....
ar.delete(15)
=> 15
ar
=> [1, 2, 3, 8, 8]

Right results, wrong output...
ar.slice!(ar.index(15))
=> 15
ar
=> [1, 2, 3, 8, 15, 8]

and also surprised me by not handling 'nil' as I wanted...
ar.slice!(ar.index(13))
TypeError: no implicit conversion from nil to integer
         from (irb):8:in `slice!'
         from (irb):8


I mean, this seems so, er, obvious! "Please find one instance of this 
object in the array, and return to me the array without that object. If 
the array doesn't have that object, then just give the array back to 
me."

Why isn't that the Ruby Way? What am I missing here?

Help?