Perform a Yelp Review Search based on a geopoint and radius tuple.

        Args:
          lat      - geopoint latitude 
          long     - geopoint longitude  
          radius   - search radius (in miles)
          term     - Search term to filter by (Optional)
          num_biz_requested - Maximum number of matching results to return (Optional)
          category - '+'-seperated list of categories to filter by. See
        http://www.yelp.com/developers/documentation/category_list
        			  for list of valid categories. (Optional)

def by_geopoint(self, lat, long, radius, term=None, num_biz_requested=None, category=None):
        """
        Perform a Yelp Review Search based on a geopoint and radius tuple.

        Args:
          lat      - geopoint latitude 
          long     - geopoint longitude  
          radius   - search radius (in miles)
          term     - Search term to filter by (Optional)
          num_biz_requested - Maximum number of matching results to return (Optional)
          category - '+'-seperated list of categories to filter by. See
        http://www.yelp.com/developers/documentation/category_list
        			  for list of valid categories. (Optional)

        """
        
        header, content = self._http_request(
            self.BASE_URL,
            lat    = lat, 
            long   = long, 
            radius = radius, 
            term   = None, 
            num_biz_requested = None
        )		
        return json.loads(content)