new_contents: from collections import Counter
  
  if __name__ == '__main__':
  
      with open('data/rosalind_dna.txt', mode='r') as f:
          sequence = f.read()
  
      counts = Counter(sequence)
  
      print '%d %d %d %d' % (counts['A'], counts['C'], counts['G'], counts['T'])
  
subject: Add solution for counting DNA nucleotides