How to use the uritemplate.variable.URIVariable function in uritemplate

def test_post_parse_plus(self):
        v = self.v
        v.operator = '+'
        v.post_parse()
        self.assertEqual(v.join_str, ',')
        self.assertEqual(v.safe, variable.URIVariable.reserved)
        self.assertEqual(v.start, '')

def parse(self):
        """Parse the variable.

        This finds the:
            - operator,
            - set of safe characters,
            - variables, and
            - defaults.

        """
        var_list = self.original
        if self.original[0] in URIVariable.operators:
            self.operator = self.original[0]
            var_list = self.original[1:]

        if self.operator in URIVariable.operators[:2]:
            self.safe = URIVariable.reserved

        var_list = var_list.split(',')

        for var in var_list:
            default_val = None
            name = var
            if '=' in var:
                name, default_val = tuple(var.split('=', 1))

            explode = False
            if name.endswith('*'):
                explode = True
                name = name[:-1]

            prefix = None

def __init__(self, uri):
        #: The original URI to be parsed.
        self.uri = uri
        #: A list of the variables in the URI. They are stored as
        #: :class:`URIVariable`\ s
        self.variables = [
            URIVariable(m.groups()[0]) for m in template_re.finditer(self.uri)
        ]
        #: A set of variable names in the URI.
        self.variable_names = OrderedSet()
        for variable in self.variables:
            for name in variable.variable_names:
                self.variable_names.add(name)