input: Write a python function to create an instance of the Counter class and test its methods.
  assert test_counter() == 1
  assert test_counter() == 0
  assert test_counter() == -1
output: def test_counter():
      class Counter:
          def __init__(self):
              self.value = 0
          
          def increment(self):
              self.value += 1
              
          def decrement(self):
              self.value -= 1
              
          def get_value(self):
              return self.value
      
      counter = Counter()
      counter.increment()
      result = counter.get_value()
      counter.decrement()
      counter.decrement()
      return result