'Process the data in multidimensional columns.'

def __call__(self, cols, meta):

    new_cols = []
    col_num = 0
    while (col_num < len(cols)):
        col = cols[col_num]
        if hasattr(col, 'colspan'):
            span_cols = cols[col_num:(col_num + col.colspan)]
            new_col = core.Column(col.name)
            new_col.str_vals = list(zip(*[x.str_vals for x in span_cols]))
            new_cols.append(new_col)
            col_num += col.colspan
        else:
            new_cols.append(col)
            col_num += 1
    return super(HTMLOutputter, self).__call__(new_cols, meta)
