code: def download_all(self, layers, force=False):
          
          layer_dirs = []
          for layer in layers:
              layer_dirs.append(self.download(layer, force))
  
          return layer_dirs
docs: Download a list of layers to the cache
  
          Parameters
          ----------
          layers list(samcli.commands.local.lib.provider.Layer)
              List of Layers representing the layer to be downloaded
          force bool
              True to download the layer even if it exists already on the system
  
          Returns
          -------
          List(Path)
              List of Paths to where the layer was cached