Define a new instance method on the Array class called second, which returns the second item in an array (similar
to the way .first and .last work in Ruby).
If there is no element with index 1 in the array, return nil.
class Array
end[3, 4, 5].second # => 4
[].second # => nilclass Array
def second
self[1]
end
endclass Array
def second
self.at(1)
end
end