docs: public void sanityCheck() {
  		for( View v : nodes ) {
  			for( Motion m : v.connections ) {
  				if( m.viewDst != v && m.viewSrc != v )
  					throw new RuntimeException("Not member of connection");
  			}
  		}
  		for( Motion m : edges ) {
  			if( m.viewDst != m.destination(m.viewSrc) )
  				throw new RuntimeException("Unexpected result");
  		}
  
  	}