Shared Rust source-expression helpers for Kiwi Rustler generator modules.
These helpers keep schema-generic renderer modules focused on decoder shape while centralizing primitive decoder expressions and small formatting details.
@spec ident(String.t() | atom()) :: String.t()
@spec indent(iodata(), non_neg_integer()) :: String.t() | []
@spec primitive(String.t()) :: String.t() | nil
@spec skip_primitive(String.t()) :: String.t() | nil