def init_copy_embeddings(old_embeddings, new_num_tokens):
    r"""
    This function aims to reduce the embeddings in case new_num_tokens < old_num_tokens or to pad with -1 in case
    new_num_tokens > old_num_tokens. A mask is also computed in order to know which weight in the embeddings should be
    kept or not. Example:

        - if new_num_tokens=5 and old_num_tokens=4 and old_embeddings=[w1,w2,w3,w4]

            -  mask=[True,True,True,True,False] and current_weights=[w1,w2,w3,w4,-1]
        - if new_num_tokens=4 and old_num_tokens=5 and old_embeddings=[w1,w2,w3,w4,w5]

            - mask=[True,True,True,True] and current_weights=[w1,w2,w3,w4]
    """
    old_num_tokens, old_embedding_dim = shape_list(old_embeddings)
    size_diff = new_num_tokens - old_num_tokens

    # initialize new embeddings
    # Copy token embeddings from the previous ones
    if tf.math.greater(size_diff, 0):
        # if the new size is greater than the old one, we extend the current embeddings with a padding until getting new size
        # and we create a mask to properly identify the padded values and be replaced by the values of the newly created
        # embeddings
        current_weights = tf.pad(
            old_embeddings.value(), tf.convert_to_tensor([[0, size_diff], [0, 0]]), constant_values=-1
        )
        num_tokens_to_copy = min(old_num_tokens, new_num_tokens)
        mask = tf.fill(tf.convert_to_tensor([num_tokens_to_copy, 1]), True)
        mask = tf.pad(mask, tf.convert_to_tensor([[0, size_diff], [0, 0]]), constant_values=False)
    else:
        # if the new size if lower than the old one, we take the current embeddings until the new size
        current_weights = tf.slice(
            old_embeddings.value(),
            tf.convert_to_tensor([0, 0]),
            tf.convert_to_tensor([new_num_tokens, old_embedding_dim]),
        )
        mask = tf.fill(tf.convert_to_tensor([new_num_tokens, 1]), True)

    return mask, current_weights

    This function aims to reduce the embeddings in case new_num_tokens < old_num_tokens or to pad with -1 in case
    new_num_tokens > old_num_tokens. A mask is also computed in order to know which weight in the embeddings should be
    kept or not. Example:

        - if new_num_tokens=5 and old_num_tokens=4 and old_embeddings=[w1,w2,w3,w4]

            -  mask=[True,True,True,True,False] and current_weights=[w1,w2,w3,w4,-1]
        - if new_num_tokens=4 and old_num_tokens=5 and old_embeddings=[w1,w2,w3,w4,w5]

            - mask=[True,True,True,True] and current_weights=[w1,w2,w3,w4]
    
dpkd/transformers/src/transformers/modeling_tf_utils.py