Exports the contents of the table to a CSV-formatted file.
           @param csv_dest: CSV file - if a string is given, the file with that name will be
               opened, written, and closed; if a file object is given, then that object
               will be written as-is, and left for the caller to be closed.
           @type csv_dest: string or file
           @param fieldnames: attribute names to be exported; can be given as a single
               string with space-delimited names, or as a list of attribute names
           @type fieldnames: list of strings
           @param encoding: string (default="UTF-8"); if csv_dest is provided as a string
               representing an output filename, an encoding argument can be provided (Python 3 only)
           @type encoding: string

def csv_export(self, csv_dest, fieldnames=None, encoding="UTF-8"):
        """Exports the contents of the table to a CSV-formatted file.
           @param csv_dest: CSV file - if a string is given, the file with that name will be
               opened, written, and closed; if a file object is given, then that object
               will be written as-is, and left for the caller to be closed.
           @type csv_dest: string or file
           @param fieldnames: attribute names to be exported; can be given as a single
               string with space-delimited names, or as a list of attribute names
           @type fieldnames: list of strings
           @param encoding: string (default="UTF-8"); if csv_dest is provided as a string
               representing an output filename, an encoding argument can be provided (Python 3 only)
           @type encoding: string
        """
        close_on_exit = False
        if isinstance(csv_dest, basestring):
            if PY_3:
                csv_dest = open(csv_dest, 'w', newline='', encoding=encoding)
            else:
                csv_dest = open(csv_dest, 'wb')
            close_on_exit = True
        try:
            if fieldnames is None:
                fieldnames = list(_object_attrnames(self.obs[0]))
            if isinstance(fieldnames, basestring):
                fieldnames = fieldnames.split()

            csv_dest.write(','.join(fieldnames) + NL)
            csvout = csv.DictWriter(csv_dest, fieldnames, extrasaction='ignore', lineterminator=NL)
            if hasattr(self.obs[0], "__dict__"):
                csvout.writerows(o.__dict__ for o in self.obs)
            else:
                do_all(csvout.writerow(ODict(starmap(lambda obj, fld: (fld, getattr(obj, fld)),
                                                     zip(repeat(o), fieldnames)))) for o in self.obs)
        finally:
            if close_on_exit:
                csv_dest.close()