Load data from file using a specified parser.

        Return value will be separated or sliced into a column list

        Parameters
        ----------
        filename : string
            A data file path
        using : list of integer, slice instance, or None, optional
            A list of index or slice instance used to slice data into column
            If it is not specified, :attr:`using` specified in constructor
            will be used instead.
        parser : instance or None, optional
            An instance or registered name of parser class.
            If it is not specified, :attr:`parser` specified in constructor
            will be used instead.

        Returns
        -------
        ndarray
            A list of numpy array

def load(self, filename, using=None, parser=None, **kwargs):
        """
        Load data from file using a specified parser.

        Return value will be separated or sliced into a column list

        Parameters
        ----------
        filename : string
            A data file path
        using : list of integer, slice instance, or None, optional
            A list of index or slice instance used to slice data into column
            If it is not specified, :attr:`using` specified in constructor
            will be used instead.
        parser : instance or None, optional
            An instance or registered name of parser class.
            If it is not specified, :attr:`parser` specified in constructor
            will be used instead.

        Returns
        -------
        ndarray
            A list of numpy array

        """
        using = using or self.using
        parser = parser or self.parser
        if parser is None:
            raise AttributeError("A parser instance must be specified")
        # parse iterator with the specified parser
        data = parser.load(filename, **kwargs)
        # slice column by using
        return slice_columns(data, using)