input: Write a function to create a dictionary in Python with given key-value pairs. The function should take two parameters: key and value, and it should return a dictionary with the specified key-value pair. If no key or value is provided, it should return an empty dictionary.
  assert create_dictionary("FirstName", "John")=={"FirstName": "John"}
  assert create_dictionary(None, "John")=={}
  assert create_dictionary("FirstName", None)=={}
  assert create_dictionary(None, None)=={}
output: def create_dictionary(key=None, value=None):
      if key is None or value is None:
          return {}
      return {key: value}