function Map(){
   this.map    =  new Object();
   this.length = 0;
   
   this.size = function(){
       return this.length;
   }
   
   this.put = function(key, value){
      
      if( !this.map["_" + key])
        {
             ++this.length;
        }
      
      this.map["_" + key] = value;
     
   }
   
   this.remove = function(key){
       
       if(this.map["_" + key])
      {
          
          --this.length;
        return delete this.map["_" + key];
      }
      else
      {
          return false;
      }
   }
   
   this.containsKey = function(key){
    
     return this.map["_" + key] ? true:false;
   
   }
    
   this.get = function(key){    
  
      return this.map["_" + key] ? this.map["_" + key]:null;
  
   }


 this.inspect=function(){    
     var str = "";
     
     for(var each in this.map)
     {
          str+= "\n"+ each + "  Value:"+ this.map[each];
     }
     
     return str;
   }
     
}