title: How to add values to a dictionary where it's key already exists
body: <p>I have a for loop which gives me multiple lists containing 2 values. This is the for loop, the data is taken from an excel file.
  Problem arise when I want to add a value to a dictionary where it's key already exists</p>
  <pre class="lang-py prettyprint-override"><code>obj={}
  test = ['Tonya Baker - Designer - noemail', ' Jess Huang - Designer - noemail', ' Denise Leung - Bizdev - noemail', ' Kristin Saulsbury - Bizdev - noemail', ' Molly Murphy - Bizdev - noemail', ' Angela Wood - Support - noemail', ' Heather Bond - Support - noemail', ' Natalie Ruiz - Support - noemail', ' Ivan Torres - Software - noemail', ' Max Gordon - Software - noemail', ' Jon Skulski - Software - noemail', ' Peggy Lin - Engineering - noemail', ' Andy Mai - Engineering - noemail', ' Alex Battaglino - Engineering - noemail', ' Evan Marks - Other - noemail', ' August Flanagan - Other - noemail', ' Helen Chi - Other - noemail', ' Ian Pearce - Other - noemail', ' Lisa Lamb - Marketing - noemail', ' Kate Levy - Marketing - noemail', ' Queen Tuba - Marketing - noemail', ' Crystal Baik - Marketing - noemail', ' Melissa Grant - Director - noemail', ' Scott Halcomb - Director - noemail', ' 
  Victoria McCulloh - Manager - noemail', ' Shawn Warehouse - Manager - noemail', ' Shawn Norwood - Manager - noemail', ' Alex Bronson - Manager - noemail', ' Noah Solnick - Manager - noemail', ' Natalie Gordon - Csuite - noemail']
  for i in test:
      arr = i.lstrip(' ').rstrip(' ').split(' - ')
      if arr[2] == 'noemail':
          arr = arr[:2]
      print(arr)  
  # gives multiple arrays [['Tonya Baker', 'Designer'], ['Jess Huang', 'Designer']]
      obj[arr[1]] = arr[0]
  print(obj)  # {'Designer': ['Jess Huang']}
  </code></pre>
  <p>But instead i want to it to be like :</p>
  <pre class="lang-py prettyprint-override"><code>{'Designer': ['Tonya Baker' ,'Jess Huang']}
  </code></pre>