title: TypeError: slice indices must be integers or None or have an __index__ method
body: <p>When running the code in IDLE gives the following error:</p>
  
  <pre><code>Traceback (most recent call last):   File "C:/Python34/inversion3.py",
  line 44, in &lt;module&gt;
      nInversions.inversionMergeSort(m)   File "C:/Python34/inversion3.py", line 16, in inversionMergeSort
       left = m[0:half] TypeError: slice indices must be integers or None or have an __index__ method
  </code></pre>
  
  <p><strong>CODE:-</strong></p>
  
  <pre><code>from collections import deque
  
  m = []
  f = open("IntegerArray.txt")
  for line in f:
      m.append(int(line))
  
  class InversionCount:
  
      def __init__(self, n):
          self.n = n
      def inversionMergeSort(self, m):
          if len(m) &lt;= 1:
              return m
          half = len(m)/2
          left = m[0:half]
          right = m[half:]
          left = self.inversionMergeSort(left)
          right = self.inversionMergeSort(right)
          return self.inversionSort(left, right)
  
      def inversionSort(self, left, right):
          leftQueue = deque(i for i in left)
          rightQueue = deque(j for j in right)
          orderedList = []
          while len(leftQueue) &gt; 0 or len(rightQueue) &gt; 0:
              if len(leftQueue) &gt; 0 and len(rightQueue) &gt; 0:
                  if leftQueue[0] &lt;= rightQueue[0]:
                      orderedList.append(leftQueue[0])
                      leftQueue.popleft()
                  else:
                      orderedList.append(rightQueue[0])
                      self.n += len(leftQueue)
                      rightQueue.popleft()
              elif len(leftQueue) &gt; 0:
                  orderedList.append(leftQueue[0])
                  leftQueue.popleft()
              elif len(rightQueue) &gt; 0:
                  orderedList.append(rightQueue[0])
                  rightQueue.popleft()
          return orderedList
  
  nInversions = InversionCount(0)
  nInversions.inversionMergeSort(m)
  print (nInversions.n)
  </code></pre>