Function is_cup_row1_col1 

fn is_cup_row1_col1(params: &[u8]) -> bool

Does a CUP (\x1b[<params>H) params string address row 1, column 1 (“home”)? Each field defaults to 1 when empty, per ECMA-48 — so "", "1", "1;1", ";1", "1;", and ";" are all row-1-col-1.