Python - simple words in a file histogram (sorted by count)

gistfile1.py

def load_data_file():
  with open('data.in') as f:
    for line in f:
        words = line.split()
        for word in words:
          if histogram[word] is not None:
            histogram[word]+=1
            print "Already found ({}) {}".format(word,histogram[word])
          else:
            histogram[word]=0

  gramkeys = histogram.keys()
  gramkeys = sorted(histogram.iteritems(), key=lambda (k,v): (v,k))
  for gram in gramkeys:
    print gram[0],gram[1]