Build a (weights, biases) tuples for all layers.

def init_net_params(scale, layer_sizes, rs=npr.RandomState(0)):
    """Build a (weights, biases) tuples for all layers."""
    return [(scale * rs.randn(m, n),   # weight matrix
             scale * rs.randn(n))      # bias vector
            for m, n in zip(layer_sizes[:-1], layer_sizes[1:])]