input: Write a python function to convert a string to title case.
  assert convert_to_title_case("My name is John Doe") == "My Name Is John Doe"
  assert convert_to_title_case("hello world") == "Hello World"
  assert convert_to_title_case("PYTHON programming") == "Python Programming"
output: def convert_to_title_case(s):
      return s.title()