syntax? in scheme/Guile

hello,

any idea for a predicate for syntax object in Guile/scheme like exist in
Racket 'syntax?' ?

i'm started writing something but i do not understand this part of R6RS:

https://www.r6rs.org/final/html/r6rs-lib/r6rs-lib-Z-H-13.html#node_sec_12.2

what examples can be done for :
-

-a nonpair, nonvector, nonsymbol value, or
-

-a wrapped syntax object.
- what is a wrapped syntax object?

Damien


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