docs: def _closest_centroid(self, x):
          """Returns the index of the closest centroid to the sample
          """
          closest_centroid = 0
          distance = 10^9
  
          for i in range(self.n_clusters):
              current_distance = linalg.norm(x - self.centroids[i])
              if current_distance < distance:
                  closest_centroid = i
                  distance = current_distance
  
          return closest_centroid