def make_update(model, docs, optimizer, drop=<NUM_LIT:0.0>, objective="<STR_LIT>"):
predictions, backprop = model.begin_update(docs, drop=drop)<EOL>loss, gradients = get_vectors_loss(model.ops, docs, predictions, objective)<EOL>backprop(gradients, sgd=optimizer)<EOL>return float(loss)<EOL>
Perform an update over a single batch of documents.

    docs (iterable): A batch of `Doc` objects.
    drop (float): The droput rate.
    optimizer (callable): An optimizer.
    RETURNS loss: A float for the loss.