Specific linear classifier in TensorFlow: input element as vector

How can I implement such linear classifier in TensorFlow:

x1*w1 + x2*w2 + x3*w3 = y_pred,

where x1, x2, x3 - vectors and w1, w2 and w3 - scalars?

I have nice tutorial for case where x1, x2, x3 - scalars (link),

but for case where x1, x2, x3 are vectors I have no realization ideas.

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