code: def cosine_alt(h1, h2): # 17 us @array, 42 us @list \w 100 bins
      r
      h1, h2 = __prepare_histogram(h1, h2)
      return -1 * float(scipy.sum(h1 * h2)) / (scipy.sum(scipy.power(h1, 2)) * scipy.sum(scipy.power(h2, 2)))
docs: r"""
      Alternative implementation of the `cosine` distance measure.
      
      Notes
      -----
      Under development.