Note that `opt_einsum` is no longer fully merged with NumPy (and likely will not be) as we now support a wider range of inputs, backends (TensorFlow, Dask, etc)

Note that `opt_einsum` is no longer fully merged with NumPy (and likely will not be) as we now support a wider range of inputs, backends (TensorFlow, Dask, etc), and more powerful optimization algorithms for expressions with hundreds of tensors. Disclaimer: I am the author of the `opt_einsum` package.