title: Writing a function for taking two argument with potential key and a dictionary name
body: <p>I have been working on this question, I have tried a couple different codes like</p>
  <pre><code>test_dictionary = {1:'a', 2:'b', 3:'c', 4:'d'}
  
  def show_value():
      i = ()
      if i in test_dictionary:
          pass
  else:
      print((i)('is not a valid key'))
  </code></pre>
  <p><em>and</em></p>
  <pre><code>test_dictionary = {1:'a', 2:'b', 3:'c', 4:'d'}
  
  def show_value(i, test_dictionary):
      if i in test_dictionary:
          pass
      else:
          print(i, 'is not a valid key')
  </code></pre>
  <p>I have to write a function using <code>show_value()</code> that takes two arguments</p>
  <ul>
  <li>a potential key and</li>
  <li>a dictionary name.</li>
  </ul>
  <p>If the potential key is in the dictionary, the function should return the value for that key. If the potential key, say invalid_key, is not in the dictionary, it should return the string:</p>
  <p>invalid_key is not a valid key.</p>
  <p>what is it I am doing wrong? I cannot figure this out?</p>