code: def add_sync_methods(cls):
    
    for name in cls.__dict__.keys():
      if name.endswith('_async'):
        sync_name = name[:-6]
        if not hasattr(cls, sync_name):
          setattr(cls, sync_name, _make_sync_method(name))
    return cls
docs: Class decorator to add synchronous methods corresponding to async methods.
  
    This modifies the class in place, adding additional methods to it.
    If a synchronous method of a given name already exists it is not
    replaced.
  
    Args:
      cls: A class.
  
    Returns:
      The same class, modified in place.