If

    pub const If = struct {
        /// Points to the first token after the `|`. Will either be an identifier or
        /// a `*` (with an identifier immediately after it).
        payload_token: ?TokenIndex,
        /// Points to the identifier after the `|`.
        error_token: ?TokenIndex,
        /// Populated only if else_expr != .none.
        else_token: TokenIndex,
        ast: Components,

        pub const Components = struct {
            if_token: TokenIndex,
            cond_expr: Node.Index,
            then_expr: Node.Index,
            else_expr: Node.OptionalIndex,
        };
    }