title: How to reverse_complementary several strings in a list
body: <p>How can I get the complementary reverse for dna? following formula works for first string but when I add the second string in the list it does not work. </p>
  
  <pre><code>dna = ['CAG', 'AGT']
  
  def reverse_complementary (char):
      my_dictionary = {"A": "T", "C": "G", "G": "C", "T": "A"} 
      return "".join([my_dictionary[i] for i in reversed(char)])
  
  print("reverse_complementary =" , reverse_complementary(dna))
  </code></pre>