Function cut_fields 

pub fn cut_fields(
    line: &[u8],
    delim: u8,
    ranges: &[Range],
    complement: bool,
    output_delim: &[u8],
    suppress_no_delim: bool,
    out: &mut impl Write,
) -> Result<bool>

Cut fields from a line using a delimiter. Writes to out. Returns true if any output was written, false if suppressed. Used by process_cut_reader (stdin path) and unit tests.