input: Write a function to create a Python script that adds two numbers together and prints the result. The function should take two parameters, `a` and `b`, add them together, and print the result. If either parameter is not provided, use 0 as the default value.
  
  def add(a=0, b=0):
      sum = a + b
      print(sum)
  
  add(5, 7)
  add(3)
  add()
output: def add(a=0, b=0):
      sum = a + b
      print(sum)