[NTG-context] How to quote the section names in advance like the table of contents?

Dear List, say I have three sections in the document: \section{foo} ... \section{bar} ... \section{baz} ... Now I would like to auto generate a heavily customized table of contents like the following text, which cannot be done by the stock \placecontent in general, and put it into the preface: This book has 3 sections: foo, bar, and baz. The text generation should be trivial with lua, but I don't know how such forward reference of section names works. Could anyone help me with it? Thanks in advance. Best, Sylvain