docs: def fsync(self, **kwargs):
          """Flush all pending writes to datafiles.
  
          :Parameters:
  
              Optional parameters can be passed as keyword arguments:
  
              - `lock`: If True lock the server to disallow writes.
              - `async`: If True don't block while synchronizing.
  
              .. warning:: `async` and `lock` can not be used together.
  
              .. warning:: MongoDB does not support the `async` option
                           on Windows and will raise an exception on that
                           platform.
          """
          self.admin.command("fsync",
                             read_preference=ReadPreference.PRIMARY, **kwargs)