@spec valid?(String.t()) :: boolean()

Returns true when value is a valid country flag, otherwise false.

Guard — returns true when value is a valid country flag.

Can be used in function heads:

def handle(v) when Elixir.Appwrite.Consts.Flag.valid_value(v), do: :ok

@spec validate(String.t()) :: {:ok, String.t()} | {:error, String.t()}

Returns {:ok, value} if valid, or {:error, "Invalid country flag"}.

@spec validate!(String.t()) :: String.t()

Returns value if valid. Raises ArgumentError otherwise.

@spec values() :: [String.t()]

Returns all valid country flag values.