code: def _generate_dockerfile(base_image, layers):
          
          dockerfile_content = "FROM {}\n".format(base_image)
  
          for layer in layers:
              dockerfile_content = dockerfile_content + \
                                   "ADD --chown=sbx_user1051:495 {} {}\n".format(layer.name, LambdaImage._LAYERS_DIR)
          return dockerfile_content
docs: Generate the Dockerfile contents
  
          A generated Dockerfile will look like the following:
          ```
          FROM lambci/lambda:python3.6
  
          ADD --chown=sbx_user1051:495 layer1 /opt
          ADD --chown=sbx_user1051:495 layer2 /opt
          ```
  
          Parameters
          ----------
          base_image str
              Base Image to use for the new image
          layers list(samcli.commands.local.lib.provider.Layer)
              List of Layers to be use to mount in the image
  
          Returns
          -------
          str
              String representing the Dockerfile contents for the image