Function parse_stream_with_prefix 

pub fn parse_stream_with_prefix(input: &str, prefix: &str) -> SyntaxNode

Like parse_stream, but treats prefix (e.g. hashpipe "#|") as an embedded-YAML per-line marker: the scanner excludes it from column/indent accounting and the builder peels it into YAML_LINE_PREFIX leaves, so the resulting CST’s token ranges are host ranges directly (prefix bytes included as trivia, no offset remapping). An empty prefix behaves like parse_stream.

prefix may be a composite marker — a container prefix prepended to #| (e.g. " #|" for a list-indented cell, "> #|" for a blockquoted one). Within a hashpipe preamble the container prefix is uniform per line, so matching the whole composite marker via strip_prefix parses a nested cell identically to a top-level one, peeling the entire prefix into one YAML_LINE_PREFIX leaf. The host computes this marker (see parse_fenced_code_block).