backward-containing-sexp in color:text<%>

• (send a-color:text backward-containing-sexp) -> void

  
  

• (send a-color:text backward-containing-sexp position cutoff) -> (union natural-number? false?)
     position : natural-number?
     cutoff : natural-number?

  Return the starting position of the interior of the (non-atomic) s-expression containing position, or #f is there is none.

  Must only be called while the tokenizer is started.