Dead code to investigate

[irevoire]

Hey,

I noticed some dead code in the euclidean & manhattan distance;

arroy/src/distance/euclidean.rs

Lines 54 to 60 in 973f093

	normal.header.bias = normal
	.vector
	.iter()
	.zip(node_p.vector.iter())
	.zip(node_q.vector.iter())
	.map(|((n, p), q)| -n * (p + q) / 2.0)
	.sum();

arroy/src/distance/manhattan.rs

Lines 57 to 63 in 973f093

	normal.header.bias = normal
	.vector
	.iter()
	.zip(node_p.vector.iter())
	.zip(node_q.vector.iter())
	.map(|((n, p), q)| -n * (p + q) / 2.0)
	.sum();

Before deleting it, we should investigate and try to understand if we were not supposed to be doing this operation in the pre-process or somewhere else?
Are the bias even set anywhere?