def to_int(self, *cols, **kwargs):
        """
        Convert some column values to integers

        :param \*cols: names of the colums
        :type \*cols: str, at least one
        :param \*\*kwargs: keyword arguments for ``pd.to_numeric``
        :type \*\*kwargs: optional

        :example: ``ds.to_int("mycol1", "mycol2", errors="coerce")``
        """
        try:
            for col in cols:
                self.df[col] = pd.to_numeric(self.df[col], **kwargs)
        except Exception as e:
            self.err(e, "Can not convert column values to integer")
            return
        self.ok("Converted column values to integers")