input: Write a function to create a class named Car in Python that stores and processes data for a car object. The class should have an initializer method to set the make, model, color, and mileage of the car. It should also have methods to accelerate and decelerate the car by setting the speed.
  
  class Car:
      def __init__(self, make, model, color, mileage):
          self.make = make
          self.model = model
          self.color = color
          self.mileage = mileage
  
      def accelerate(self, speed):
          self.speed = speed
  
      def decelerate(self, speed):
          self.speed = speed
  
  assert Car("Toyota", "Camry", "Red", 50000).make=="Toyota"
  assert Car("Honda", "Accord", "Blue", 40000).model=="Accord"
  assert Car("Ford", "Mustang", "Yellow", 30000).color=="Yellow"
  assert Car("Nissan", "Altima", "Black", 60000).mileage==60000
  car = Car("Tesla", "Model S", "White", 20000)
  car.accelerate(60)
  assert car.speed==60
  car.decelerate(40)
  assert car.speed==40
output: def __init__(self, make, model, color, mileage):
      self.make = make
      self.model = model
      self.color = color
      self.mileage = mileage
      self.speed = 0
  
  def accelerate(self, speed):
      self.speed = speed
  
  def decelerate(self, speed):
      self.speed = speed