/**
 * Returns the cosine similarity between the given `vectorA` and `vectorB`.
 * Returns `0` when given a zero vector, `[]`, `undefined` or nothing.
 *
 * @param vectorA The first vector.
 * @param vectorB The second vector.
 * @returns The cosine similarity between the two vectors.
 */
export default function cosineSimilarity(
  vectorA?: number[],
  vectorB?: number[],
): number;