input: Write a function that implements the IntList class described in the instruction. The class should be able to store integer values and find the minimum value among them. The class should have an add_value method to add new values and a find_min method to return the minimum value.
  class IntList:
      def __init__(self):
          self.values = []
     
      def add_value(self, value):
          self.values.append(value)
      
      def find_min(self):
          return min(self.values)
  
  assert IntList().find_min()==float('inf')
  assert IntList().add_value(10).add_value(5).add_value(20).find_min()==5
  assert IntList().add_value(-1).add_value(-5).add_value(-2).find_min()==-5
  assert IntList().add_value(0).find_min()==0
output: class IntList:
      def __init__(self):
          self.values = []
     
      def add_value(self, value):
          self.values.append(value)
          return self
      
      def find_min(self):
          return min(self.values, default=float('inf'))