Return a string with data in CSV format

def to_csvline(self, with_header=False):
        """Return a string with data in CSV format"""
        string = ""

        if with_header:
            string += "# " + " ".join(at for at in AbinitTimerSection.FIELDS) + "\n"

        string += ", ".join(str(v) for v in self.to_tuple()) + "\n"
        return string