
  [;1m-spec get_keys() -> [Key] when Key :: term().[0m

[;;4mSince[0m:
  OTP 18.0

  Returns a list of all keys present in the process dictionary. The
  items in the returned list can be in any order. Example:

    > put(dog, {animal,1}),
    put(cow, {animal,2}),
    put(lamb, {animal,3}),
    get_keys().
    [dog,cow,lamb]

  [;1m-spec get_keys(Val) -> [Key] when Val :: term(), Key :: term().[0m

  Returns a list of keys that are associated with the value [;;4mVal[0m in
  the process dictionary. The items in the returned list can be in
  any order. Example:

    > put(mary, {1, 2}),
    put(had, {1, 2}),
    put(a, {1, 2}),
    put(little, {1, 2}),
    put(dog, {1, 3}),
    put(lamb, {1, 2}),
    get_keys({1, 2}).
    [mary,had,a,little,lamb]
