def METHOD_NAME(identifier):
    """Retrieves a Keras loss as a `function`/`Loss` class instance.
    The `identifier` may be the string name of a loss function or `Loss` class.
    >>> loss = losses.get("categorical_crossentropy")
    >>> type(loss)
    <class 'function'>
    >>> loss = losses.get("CategoricalCrossentropy")
    >>> type(loss)
    <class '...CategoricalCrossentropy'>
    You can also specify `config` of the loss to this function by passing dict
    containing `class_name` and `config` as an identifier. Also note that the
    `class_name` must map to a `Loss` class
    >>> identifier = {"class_name": "CategoricalCrossentropy",
    ...               "config": {"from_logits": True}}
    >>> loss = losses.get(identifier)
    >>> type(loss)
    <class '...CategoricalCrossentropy'>
    Args:
        identifier: A loss identifier. One of None or string name of a loss
            function/class or loss configuration dictionary or a loss function
            or a loss class instance.
    Returns:
        A Keras loss as a `function`/ `Loss` class instance.
    """
    if identifier is None:
        return None
    if isinstance(identifier, dict):
        obj = deserialize(identifier)
    elif isinstance(identifier, str):
        obj = deserialize(identifier)
    else:
        obj = identifier
    if callable(obj):
        return obj
    else:
        raise ValueError(f"Could not interpret loss identifier: {identifier}")