title: How to check arguments passed to the function call are empty?
body: <p>I want the function to simply check if an argument is passed or not. If not, print something, else say some hello and that argument.</p>
  
  <p>Here is sample of my code:</p>
  
  <pre><code>def say_name(name):
    if name is None:
      print("Hello there")
    else:
      print("Hello, "+ name + "!")
  </code></pre>
  
  <p>run code:</p>
  
  <pre><code>class Test(unittest.TestCase):
    def test_should_say_hello(self):
      self.assertEqual(say_name("Michael"), "Hello, Michael!")
  </code></pre>
  
  <p>I have tried using <code>None</code>, Kwargs and still not working. <strong>How can I check whether argument is passed to the function?</strong></p>