Maya. File contains unknown nodes or data

Solving "File contains unknown nodes or data" error in Maya:

string $unknownNodes[] = `lsType unknown`;
 for($node in $unknownNodes){
 if($node=="<done>")
 break;
 if(`objExists $node`){
 int $lockState[] = `lockNode -q -l $node`;
 if($lockState[0]==1)
 lockNode -l off $node;
 delete $node;
 }
 }

Source:
https://www.reddit.com/r/Maya/comments/4du7jt/file_contains_unknown_nodes_or_data/