docs: def add_file_to_tree(tree, file_path, file_contents, is_executable=False):
      """Add a file to a tree.
  
      Args:
  
          tree
              A list of dicts containing info about each blob in a tree.
  
          file_path
              The path of the new file in the tree.
  
          file_contents
              The (UTF-8 encoded) contents of the new file.
  
          is_executable
              If ``True``, the new file will get executable permissions (0755).
              Otherwise, it will get 0644 permissions.
  
      Returns:
          The provided tree, but with the new file added.
  
      """
      record = {
          "path": file_path,
          "mode": "100755" if is_executable else "100644",
          "type": "blob",
          "content": file_contents,
          }
      tree.append(record)
      return tree