func_code: def intersection(a, b):
      i = 0
      s = []
      while i < len(a) and i < len(b):
          if a[i] in b:
              s.append(a[i])
          i = i + 1
      return s
      n = 0
      x = []
      while n < len(s):
          if s[n] not in s:
              x.append(s[n])
          n = n + 1
      return x