string flat_map(mapping mp) {
    mapping carte = ([]);
    mixed key, val;
    string retkey, retval, retstring;

    retstring = "";

    carte = expand_keys(mp);

    foreach( key, val in carte){
	if(arrayp(key)){
	    if(!sizeof(key)) retkey = "BLANK ARRAY";
	    else retkey = "ARRAY ("+implode(key,", ")+")";
	}
	else if(objectp(key)) retkey = "OBJECT ("+file_name(key)+")";
	else if(intp(key)) retkey = ""+key;
	else retkey = key;
	if(arrayp(val)){
	    if(!sizeof(val)) retval = "BLANK ARRAY";
	    else retval = "ARRAY ("+implode(val,", ")+")";
	}
	else if(objectp(val)) retval = "OBJECT ("+file_name(val)+")";
	else if(intp(val)) retval = ""+val;
	else retval = val;

	if(!retstring || retstring == "") retstring = retkey+":"+retval;
	else retstring += ", "+retkey+":"+retval;
    }

    return retstring;

}