pub const For = struct {
    ast: Components,
    inline_token: ?TokenIndex,
    label_token: ?TokenIndex,
    payload_token: TokenIndex,
    /// Populated only if else_expr != 0.
    else_token: TokenIndex,

    pub const Components = struct {
        for_token: TokenIndex,
        inputs: []const Node.Index,
        then_expr: Node.Index,
        else_expr: Node.Index,
    };
}