title: How to let the user add 'None' to an specific array that's is set as value of an specific key in a dictionary on Python?
body: <p>Ok so, the question may sound confusing at first but I'm gonna do my best to explain what I would like to learn in order to improve my programming skills.</p>
  <p>Let's say I have a path in which exists 6 folders with the following file images:</p>
  <h3>Color:</h3>
  <blockquote>
  <p>Amarillo.png Blanco.png Rojirosado.png Turquesa.png Verde_oscuro.png Zapote.png</p>
  </blockquote>
  <h3>Cuerpo:</h3>
  <blockquote>
  <p>Cuerpo_cangrejo.png</p>
  </blockquote>
  <h3>Fondo:</h3>
  <blockquote>
  <p>Oceano.png</p>
  </blockquote>
  <h3>Ojos:</h3>
  <blockquote>
  <p>Antenas.png Pico.png Verticales.png</p>
  </blockquote>
  <h3>Pinzas:</h3>
  <blockquote>
  <p>Pinzitas.png Pinzotas.png Pinzota_pinzita.png</p>
  </blockquote>
  <h3>Puas:</h3>
  <blockquote>
  <p>Arena.png Marron.png Purpura.png Verde.png</p>
  </blockquote>
  <p>Now, I want the above information to be stored in a dictionary for further use, so I run the code below <strong>in the same path in which the folders previously mentioned exist</strong>:</p>
  <pre><code>import os
  # Main method
  the_dictionary_list = {}
  
  for name in os.listdir(&quot;.&quot;):
      if os.path.isdir(name):
          path = os.path.basename(name)
          print(f'\u001b[45m{path}\033[0m')
          list_of_file_contents = os.listdir(path)
          print(f'\033[46m{list_of_file_contents}')
          the_dictionary_list[path] = list_of_file_contents
          print('\n')
  print('\u001b[43mthe_dictionary_list:\033[0m')
  print(the_dictionary_list)
  </code></pre>
  <p><strong>So after compiling the program above I get my dictionary:</strong></p>
  <p><a href="https://i.stack.imgur.com/HqJOR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/HqJOR.png" alt="Dictionary" /></a></p>
  <p>But here's the problem: After creating the dictionary, how can I let the user decide in which arrays to add a '<strong>None</strong>' string as a new value (i.e. not replacing the current ones), meaning that, for instance, if the user wanted to add '<strong>None</strong>' only to <code>Puas</code> Array and <code>Pinzas</code> Array, it would generate the following output?:</p>
  <pre><code>the_dictionary_list: {
  'Color': ['Amarillo.png', 'Blanco.png','Rojirosado.png', 'Turquesa.png', 'Verde_oscuro.png', 
  'Zapote.png'],
  'Cuerpo': ['Cuerpo_cangrejo.png'],
  'Fondo': ['Oceano.png'], 
  'Ojos': ['Antenas.png', 'Pico.png', 'Verticales.png'],
  'Pinzas': ['None', 'Pinzitas.png', 'Pinzotas.png', 'Pinzota_pinzita.png'],
  'Puas': ['None', 'Arena.png', 'Marron.png', 'Purpura.png', 'Verde.png']}
  </code></pre>