def vstack(xs):
    """Stack tensors in sequence vertically (row wise).

    Args:
        xs: Sequence of tensors.

    Returns:
        Tensor formed by stacking the given tensors.
    """
    if any_symbolic_tensors((xs,)):
        return Vstack().symbolic_call(xs)
    return backend.numpy.vstack(xs)
Stack tensors in sequence vertically (row wise).

    Args:
        xs: Sequence of tensors.

    Returns:
        Tensor formed by stacking the given tensors.
    
keras/src/ops/numpy.py