
  [;1m-spec list_to_existing_atom(String) -> atom() when String :: string().[0m

  Returns the atom whose text representation is [;;4mString[0m, but only
  if there already exists such atom. An atom exists if it has been
  created by the run-time system by either loading code or creating
  a term in which the atom is part.

  Failure: [;;4mbadarg[0m if there does not already exist an atom whose
  text representation is [;;4mString[0m.

  Note:
    Note that the compiler may optimize away atoms. For example,
    the compiler will rewrite [;;4matom_to_list(some_atom)[0m to [;;4m[0m
    [;;4m"some_atom"[0m. If that expression is the only mention of the
    atom [;;4msome_atom[0m in the containing module, the atom will not
    be created when the module is loaded, and a subsequent call to [;;4m[0m
    [;;4mlist_to_existing_atom("some_atom")[0m will fail.