'Return all instance resources using an iterator
This will fetch a page of resources from the API and yield them in
turn. When the page is exhausted, this will make a request to the API
to retrieve the next page. Hence you may notice a pattern - the library
will loop through 50 objects very quickly, but there will be a delay
retrieving the 51st as the library must make another request to the API
for resources.
Example usage:
.. code-block:: python
for message in client.messages:
print message.sid'

def iter(self, **kwargs):

    params = urlencode(transform_params(kwargs))
    parsed = urlparse(self.uri)
    url = urlunparse(((parsed[:4] + (params,)) + (parsed[5],)))
    while True:
        (resp, page) = self.request('GET', url)
        key = page.get('meta', {}).get('key')
        if ((key is None) or (key not in page)):
            raise StopIteration()
        for ir in page[key]:
            (yield self.load_instance(ir))
        url = page.get('meta', {}).get('next_page_url')
        if (not url):
            raise StopIteration()
