text: class Sensor {
  	
  	constructor( environment ) {
  		this._environment = environment;
  	}
  	
  	canNavigate(row,col){
  		if( 0<=row && row <=9 && 0<=col && col<=9 ) {
  			return ( this._environment.grid(row,col) != 'B' );
  		} 
  
  		return false;
  	}
  
  	dirty(){
  		return this._environment.isDirty();
  	}
  	
  }