test.rb

#!/usr/bin/env ruby                                                                                                                                                                                                                          

arr1 = [ 1, 2, 2 ]
arr2 = [ 0, 1, 3 ]
@arr3 = []

def array_push(arr)
  arr.each do |element|
    if ! @arr3.include?(element)                                                                                      
      @arr3.push(element)                                                                                             
    end
  end
end

array_push arr1
array_push arr2

puts @arr3