F hash_join(table1, table2)
   DefaultDict[String, [(Int, String)]] h
   L(s) table1
      h[s[1]].append(s)

   [((Int, String), (String, String))] res
   L(r) table2
      L(s) h[r[0]]
         res [+]= (s, r)
   R res

V table1 = [(27, ‘Jonah’),
            (18, ‘Alan’),
            (28, ‘Glory’),
            (18, ‘Popeye’),
            (28, ‘Alan’)]
V table2 = [(‘Jonah’, ‘Whales’),
            (‘Jonah’, ‘Spiders’),
            (‘Alan’, ‘Ghosts’),
            (‘Alan’, ‘Zombies’),
            (‘Glory’, ‘Buffy’)]

L(row) hash_join(table1, table2)
   print(row)