Метод-член с динамической сигнатурой через декоратор

from functools import wraps


def customizable_args(new_kwargs):
    def wrapper(function):
        @wraps(function)
        def wrapped_function(self, **kwargs):
            kw_arguments = dict()
            kw_arguments.update(new_kwargs)
            kw_arguments.update(kwargs)
            function(self, **kw_arguments)
        return wrapped_function
    return wrapper


class InsertQuery:
    def __init__(self, table: str, fields: list):
        self.__table = table
        self.__fields = str()
        self.__values_pattern = str()
        arguments = str()
        for field in fields:
            if self.__fields:
                self.__fields += ', '
                arguments += ', '
            self.__fields += field
            arguments += (field + ' = None')
            if self.__values_pattern:
                self.__values_pattern += ', '
            self.__values_pattern += '%s'
        self.__insert_list = list()
        new_args = dict(zip(fields, [None for field in fields]))
        self.__make_add_record_function(new_args, fields)

    def query(self) -> str:
        return 'INSERT INTO {} ({}) VALUES ({})'.format(self.__table, self.__fields, self.__values_pattern)

    def __make_add_record_function(self, arguments, col_list):

        @customizable_args(arguments)
        def add_record(self, **kwargs):
            for col in col_list:
                self.__insert_list.append(kwargs[col])

        setattr(self.__class__, add_record.__name__, add_record)

    def insert(self):
        return self.__insert_list


statement1 = InsertQuery('cert_info', ['issuer', 'subject', 'started', 'expires'])
statement2 = InsertQuery('cert_info', ['issuer', 'subject', 'started', 'expires'])

statement1.add_record(issuer='hiu', subject='weweqe', expires='zavtra')
statement2.add_record(issuer='lio', subject='iopiop', )
print(statement1.insert())
print(statement2.insert())