input: Write a python function to format a string using input name and value.
  assert format_string("John", "42") == "Hello John, your value is 42"
  assert format_string("Alice", "98") == "Hello Alice, your value is 98"
  assert format_string("Bob", "15") == "Hello Bob, your value is 15"
output: def format_string(name, value):
      return f"Hello {name}, your value is {value}"