title: Find count of number of pairs in the list
body: <p>I have list of numbers:</p>
  <pre><code>[5, 4, 3, 4, 2, 1, 3, 5, 3, 5, 3, 5,]
  </code></pre>
  <p>A pair of numbers is the same 2 numbers. For example, 5 occurs 4 times, so we have 2 pairs of 5s. In the list above I can say I have 5 pairs. I want the output to count how many pairs of numbers are in the list.</p>
  <p>I tried this, but got stuck.</p>
  <pre><code>list = [5,4,3,4,2,1,3,5]
  print(list)
  temp = 0
  new_list = []
  for index,x in enumerate(list):
      elm_count = list.count(list[index])
      if new_list:
          for ind, y in enumerate(new_list):
              if list[index] == new_list[ind]:
                  continue
                  if not elm_count % 2:
                      occ_count = elm_count/2
                      temp += occ_count
                      new_list.append(list[index])
                      continue
  </code></pre>