input: Write a python function to convert a string to camel case.
  assert toCamelCase("hello world") == "HelloWorld"
  assert toCamelCase("this is a test string") == "ThisIsATestString"
  assert toCamelCase("convert this text") == "ConvertThisText"
output: def toCamelCase(s):
      return ''.join(word.capitalize() for word in s.split())