
  -spec get(Key) -> Val | undefined when Key :: term(), Val :: term().

  Returns the value Val associated with Key in the process
  dictionary, or undefined if Key does not exist. The expected
  time complexity for the current implementation of this function is
  O(1) and the worst case time complexity is O(N), where N is
  the number of items in the process dictionary. Example:

    > put(key1, merry),
    put(key2, lambs),
    put({any, [valid, term]}, {are, playing}),
    get({any, [valid, term]}).
    {are,playing}
