class ngrams:
  '''to represent and count a set of n-grams'''
  def __init__(self):
    self.__ngrams = {} # dictionary of n-grams (key:n-gram,value:count)
    self.__count = 0 # number of n-grams

  def add(self,n_gram):
    '''ajoute et $n_gram$ qui est une liste'''
    s = ''
    for e in n_gram:
      s += e + ','      
    n = self.__ngrams.get(s,0)
    self.__ngrams[s] = n + 1
    self.__count += 1
    
  def get(self,g):
    s = ''
    for e in g:
      s += e + ','

    return self.__ngrams.get(s)

#exemple
#n = ngrams()
#n.add(['A','A','N'])
#print n.get(['A','A','N']).__str__()