format table to *behave* example
    :param table: `(caption, rows)`, each item in `rows` is `(col1, col2,...)`
    :return

def format_to_example(table, tabspace=2, indent=2):
    """ format table to *behave* example
    :param table: `(caption, rows)`, each item in `rows` is `(col1, col2,...)`
    :return
    """
    from io import StringIO
    output = StringIO()

    caption, rows = table

    # output caption line
    output.write(u'{0}Examples: {1}\n'.format(' ' * indent * tabspace,
                                              caption))

    # calculate max length for each column, for aligning
    cols = zip(*rows)
    col_lengths = []
    for col in cols:
        max_length = max([len(format_item(row)) for row in col])
        col_lengths.append(max_length)

    # output each row
    for r, row in enumerate(rows):
        output.write(u' ' * (indent + 1) * tabspace)
        output.write(u'|')
        for c in range(len(col_lengths)):
            output.write(u' ')
            output.write(format_item(row[c], r))
            output.write(u' ' * (col_lengths[c] - len(format_item(row[c], r))))
            output.write(u' |')
        output.write(u'\n')

    example = output.getvalue()
    output.close()
    return example