fn parse_top_level_fn_def_name(line: &str) -> Option<&str>Expand description
Parse the function name from a top-level name <- function(...) definition
line, or return None when the line is not such a definition.
Recognises only top-level definitions: the line must start at column 0
(no leading whitespace – indented forms are R6/S7 closures, not standalone
wrappers) and the left-hand side must be a single bare R identifier. Lines
where the LHS is a call (e.g. S7::method(...) <- function) or contains $
/ [[ / :: are not bare definitions and are skipped.