input: Write a python function to calculate the Euclidean distance between two 3D points.
  assert euclidean_distance(Euclidean3D(1, 2, 3), Euclidean3D(4, 5, 6)) == 5.196152422706632
  assert euclidean_distance(Euclidean3D(0, 0, 0), Euclidean3D(1, 1, 1)) == 1.7320508075688772
  assert euclidean_distance(Euclidean3D(-1, -1, -1), Euclidean3D(1, 1, 1)) == 3.4641016151377544
output: import math
  
  class Euclidean3D:
      def __init__(self, x, y, z):
          self.x = x
          self.y = y
          self.z = z
  
  def euclidean_distance(point1, point2):
      return math.sqrt((point1.x - point2.x)**2 + (point1.y - point2.y)**2 + (point1.z - point2.z)**2)