Returns an :class:`Html` factory function for ``tag`` and a given
    dictionary of ``defaults`` parameters. For example::

    >>> input_factory = html_factory('input', type='text')
    >>> html = input_factory(value='bla')

def html_factory(tag, **defaults):
    '''Returns an :class:`Html` factory function for ``tag`` and a given
    dictionary of ``defaults`` parameters. For example::

    >>> input_factory = html_factory('input', type='text')
    >>> html = input_factory(value='bla')

    '''
    def html_input(*children, **params):
        p = defaults.copy()
        p.update(params)
        return Html(tag, *children, **p)
    return html_input