input: Write a python function to determine if a shape is valid based on its number of sides.
  assert Shape([5, 5, 5]).isValid() == True
  assert Shape([5, 5]).isValid() == False
  assert Shape([2, 2, 2, 2]).isValid() == True
output: class Shape:
      def __init__(self, sides):
          self.sides = sides
  
      def isValid(self):
          return len(self.sides) > 2