code: function determineDepth(obj){
  
    let depth = 0;
  
    obj.forEach((line)=>{
      
      line.depth = depth;
      
      if(line.isBlockKey){
        depth++;
      }else{
        if(line.key){
          if(line.key.toUpperCase() === 'END'){
            depth--;
            line.depth = depth;
          }
        }
      }
    });
  
    return obj;
  }
docs: Determines the depth of every line of mapfile.
  @param {array} obj Array of line objects