'html5lib tree-walkers use a dict of (namespace, name): value for
attributes, but JSON cannot represent this. Convert from the format
in the serializer tests (a list of dicts with "namespace", "name",
and "value" as keys) to html5lib\'s tree-walker format.'

def _convertAttrib(self, attribs):

    attrs = {}
    for attrib in attribs:
        name = (attrib['namespace'], attrib['name'])
        assert (name not in attrs)
        attrs[name] = attrib['value']
    return attrs
