code: def _euclidean_dist(vector_a, vector_b):
      
      dist = 0
      for (x, y) in zip(vector_a, vector_b):
          dist += (x-y)*(x-y)
      return math.sqrt(dist)
docs: :param vector_a:    A list of numbers.
      :param vector_b:    A list of numbers.
      :returns:           The euclidean distance between the two vectors.