src/main/java/org/jinstagram/realtime/InstagramSubscription.java
public InstagramSubscription radius(String radius){
		Preconditions.checkValidRadius(radius, "Invalid 'radius' key");
		
		this.params.put(Constants.RADIUS, radius);
		
		return this;
	}
public InstagramSubscription radius(String radius){
		Preconditions.checkValidRadius(radius, "Invalid 'radius' key");
		
		this.params.put(Constants.RADIUS, radius);
		
		return this;
	}
Configure the radius for geography subscription
@param radius The radius for geography subscription in metre
@return the {@link InstagramSubscription} instance for method chaining