code: def files_exist(self, file_paths):
      
      results = {}
  
      def exist_thunk(paths, interface):
        results.update(interface.files_exist(paths))
  
      if len(self._threads):
        for block in scatter(file_paths, len(self._threads)):
          self.put(partial(exist_thunk, block))
      else:
        exist_thunk(file_paths, self._interface)
  
      desc = 'Existence Testing' if self.progress else None
      self.wait(desc)
  
      return results
docs: Threaded exists for all file paths.
  
      file_paths: (list) file paths to test for existence
  
      Returns: { filepath: bool }