'A word in the sentence.
- lemma: base form of the word; "was" => "be".
-  type: the part-of-speech tag; "NN" => a noun.
- chunk: the chunk (or phrase) this word belongs to.
- index: the index in the sentence.'

def __init__(self, sentence, string, lemma=None, type=None, index=0):

    if (not isinstance(string, unicode)):
        try:
            string = string.decode('utf-8')
        except:
            pass
    self.sentence = sentence
    self.index = index
    self.string = string
    self.lemma = lemma
    self.type = type
    self.chunk = None
    self.pnp = None
    self._custom_tags = None
