[barbierocks]

Essentially correct! Instead of `1 None` it'd fail with a `KeyError`. You can get a probability distribution too:

    1 baz       1/8
    KeyError    1/8
    2 foo       1/8
    2 bar       1/4
    2 baz       3/8

[divbzero]

Indeed, I got

  Counter({
      (1, 'baz'): 12525,
      (1, 'KeyError'): 12552,
      (2, 'foo'): 12255,
      (2, 'bar'): 25282,
      (2, 'baz'): 37386
  })

from running

  import random
  
  class C:
      def __hash__(self): 
          # return 0 or 1, with equal probability
          return random.randint(0, 1)
  
  def output():
      x = C()
      d = {}
      d[x] = "foo"
      d[x] = "bar"
      d[x] = "baz"
      try:
          return len(d), d[x]
      except Exception as e:
          return len(d), type(e).__name__
  
  from collections import Counter
  Counter(output() for i in range(100000))