def __call__(self, environ, start_response):
request = api_request.ApiRequest(environ,<EOL>base_paths=self._backend.base_paths)<EOL>yield self.dispatch(request, start_response)<EOL>
Handle an incoming request.

        Args:
          environ: An environ dict for the request as defined in PEP-333.
          start_response: A function used to begin the response to the caller.
            This follows the semantics defined in PEP-333.  In particular, it's
            called with (status, response_headers, exc_info=None), and it returns
            an object with a write(body_data) function that can be used to write
            the body of the response.

        Yields:
          An iterable over strings containing the body of the HTTP response.