Append new columns to the table.

        When appending a single column, ``values`` can be a scalar or an
        array of either length 1 or the same length as this array (the one
        it's appended to). In case of multiple columns, values must have
        the shape ``list(arrays)``, and the dimension of each array
        has to match the length of this array.

        See the docs for ``numpy.lib.recfunctions.append_fields`` for an
        explanation of the remaining options.

def append_columns(self, colnames, values, **kwargs):
        """Append new columns to the table.

        When appending a single column, ``values`` can be a scalar or an
        array of either length 1 or the same length as this array (the one
        it's appended to). In case of multiple columns, values must have
        the shape ``list(arrays)``, and the dimension of each array
        has to match the length of this array.

        See the docs for ``numpy.lib.recfunctions.append_fields`` for an
        explanation of the remaining options.
        """
        n = len(self)
        if np.isscalar(values):
            values = np.full(n, values)

        values = np.atleast_1d(values)
        if not isinstance(colnames, str) and len(colnames) > 1:
            values = np.atleast_2d(values)
            self._check_column_length(values, n)

        if values.ndim == 1:
            if len(values) > n:
                raise ValueError("New Column is longer than existing table!")
            elif len(values) > 1 and len(values) < n:
                raise ValueError(
                    "New Column is shorter than existing table, "
                    "but not just one element!"
                )
            elif len(values) == 1:
                values = np.full(n, values[0])
        new_arr = rfn.append_fields(
            self, colnames, values, usemask=False, asrecarray=True, **kwargs
        )
        return self.__class__(
            new_arr,
            h5loc=self.h5loc,
            split_h5=self.split_h5,
            name=self.name,
            h5singleton=self.h5singleton
        )