phashmap_inst_coherence.lean:12:6: error: application type mismatch
  PersistentHashMap.find? m
argument
  m
has type
  PersistentHashMap Nat Nat
but is expected to have type
  PersistentHashMap Nat Nat
phashmap_inst_coherence.lean:12:0: error: failed to synthesize
  Lean.Eval ?m