phashmap_inst_coherence.lean:12:53-12:54: error: Application type mismatch: The argument
  m
has type
  @PersistentHashMap Nat Nat instBEqOfDecidableEq instHashableNat
but is expected to have type
  @PersistentHashMap Nat Nat ?m natDiffHash
in the application
  m.find?