fails:Array#drop removes the specified number of elements from the start of the array
fails:Array#drop raises an ArgumentError if the number of elements specified is negative
fails:Array#drop returns an empty Array if all elements are dropped
fails:Array#drop returns an empty Array when called on an empty Array
fails:Array#drop does not remove any elements when passed zero
fails:Array#drop returns an empty Array if more elements than exist are dropped
fails:Array#drop acts correctly after a shift
