@type arg() ::
  {atom(), fragment()}
  | {:labeled, atom(), atom(), fragment()}
  | {:repeat, atom(), [arg()]}

@type fragment() :: :expr | :ty | :ident | :literal

@type t() :: %RustQ.Meta.RustMacro.Definition{
  args: [arg()],
  body_ast: Macro.t(),
  call_ast: Macro.t(),
  name: atom(),
  rust_module: [atom()] | nil
}