Filesystem-based interprocess mutex.
| Function | unique | Undocumented | 
| Function | kill | Undocumented | 
| Function | symlink | Write a file at filenamewith the contents ofvalue. See the above comment block as to why this is 
needed. | 
| Function | readlink | Read the contents of filename. See the above comment block 
as to why this is needed. | 
| Function | rmlink | Undocumented | 
| Class | FilesystemLock | A mutex. | 
| Function | isLocked | Determine if the lock of the given name is held or not. | 
Write a file at filename with the contents of 
value. See the above comment block as to why this is 
needed.