Replace first occurrence of pat with rep in each element.

        Parameters
        ----------
        pat : str
        rep : str

        Returns
        -------
        Series

def replace(self, pat, rep):
        """Replace first occurrence of pat with rep in each element.

        Parameters
        ----------
        pat : str
        rep : str

        Returns
        -------
        Series

        """
        check_type(pat, str)
        check_type(rep, str)

        return _series_str_result(self, weld_str_replace, pat=pat, rep=rep)