'Bind a namespace to a schema location (URI).
This is used for imports that don\'t specify a schemaLocation.
@param ns: A namespace-uri.
@type ns: str
@param location: The (optional) schema location for the
namespace.  (default=ns).
@type location: str'

@classmethod
def bind(cls, ns, location=None):

    if (location is None):
        location = ns
    cls.locations[ns] = location
