Function names_of 

pub fn names_of(
    lines: &[Vec<u8>],
    read: &[usize],
    rows: &[usize],
    join: &str,
    separator: u8,
    comment: Option<&str>,
) -> Vec<String>

The names of the columns, from the lines rows names (1-based, counted from the top of the file before anything is skipped), each split on separator and trimmed; lines are the lines read names as named_lines read them, and one not read is blank.

A column’s name is its pieces from those lines, in the order rows gives them, joined with join; a blank piece adds nothing. A line that starts with comment is a header line all the same, since the user named it, and loses the prefix.