code: def _aggr_mode(inList):
    
  
    valueCounts = dict()
    nonNone = 0
  
    for elem in inList:
      if elem == SENTINEL_VALUE_FOR_MISSING_DATA:
        continue
  
      nonNone += 1
      if elem in valueCounts:
        valueCounts[elem] += 1
      else:
        valueCounts[elem] = 1
  
    # Get the most common one
    if nonNone == 0:
      return None
  
    # Sort by counts
    sortedCounts = valueCounts.items()
    sortedCounts.sort(cmp=lambda x,y: x[1] - y[1], reverse=True)
    return sortedCounts[0][0]
docs: Returns most common value seen in the non-None elements of the list