A type of resolver that allows developers to register different callable
objects to handle different URI schemes. The default action if there
is nothing registered for the scheme will be to fall back to
UriResolverBase behavior *unless* you have in the mapping a special
scheme None. The callable object that is the value on that key will
then be used as the default for all unknown schemes.
The expected function signature for scheme call-backs matches
UriResolverBase.resolve, without the instance argument:
resolve(uri, base=None)
Reminder: Since this does not include self, if you are registering
a method, use the method instance (i.e. myresolver().handler
rather than myresolver.handler)
You can manipulate the mapping directly using the "handlers" attribute.
Methods
handlers - a Python dictionary with scheme names as keys (e.g. "http")
and callable objects as values