MAIN_LOOP: while (<READ_NETLIST>) {
    chomp;
    s/^\s+//;       # Remove leading blanks (if any) in the line
    # ignore line if it contains comments or initializing words for spectre
    switch ($_) {
        case /^[*\/]/i           { next MAIN_LOOP; }
        case /simulator\s+lang/i { next MAIN_LOOP; }
        case /^include/i         { next MAIN_LOOP; }
    }
    ...
}