Ignore the `size` since a complete line must be processed.

def readline(self, size=-1):
        "Ignore the `size` since a complete line must be processed."
        while True:
            try:
                record = next(self.reader)
            except StopIteration:
                break

            # Ensure this is a valid record
            if checks.record_is_valid(record):
                # Process the line
                cleaned = self.process_line(record)
                if cleaned:
                    lines = []
                    for c in cleaned:
                        lines.append(self.outdel.join([str(x) for x in c]))
                    return '\n'.join(lines) + '\n'

        return ''