input: Write a function to create a dictionary in Python with key-value pairs. The function should take two string arguments: a key and a value, and return a dictionary containing that single key-value pair. If the function is called with no arguments, it should return an empty dictionary.
  
  assert create_dict("FirstName", "John")=={"FirstName": "John"}
  assert create_dict("LastName", "Doe")=={"LastName": "Doe"}
  assert create_dict() == {}
  assert create_dict("Age", "25") == {"Age": "25"}
  assert create_dict("", "Value") == {"": "Value"}
output: def create_dict(key="", value=""):
      if key == "" and value == "":
          return {}
      return {key: value}