title: Given a dictionary, how do I join the key and value with "_" and append them into a list?
body: <p>I have the following:</p>
  <pre><code>def dict_join_key_value(input_dict):
      for key,value in input_dict.items():
          y=[]
          x=key+'_'+value
          print(y.append(x))
      return 
  dict_join_key_value({&quot;a&quot;: &quot;b&quot;, &quot;c&quot;: &quot;d&quot;})
  </code></pre>
  <p>Somehow i was not able to produce the list ['a_b','c_d'], what changes do I need to make to my code?</p>