'Appends the next word to the sentence / chunk / preposition.
For example: Sentence.append("clawed", "claw", "VB", "VP", role=None, relation=1)
- word     : the current word,
- lemma    : the canonical form of the word,
- type     : part-of-speech tag for the word (NN, JJ, ...),
- chunk    : part-of-speech tag for the chunk this word is part of (NP, VP, ...),
- role     : the chunk\'s grammatical role (SBJ, OBJ, ...),
- relation : an id shared by other related chunks (e.g., SBJ-1 <=> VP-1),
- pnp      : PNP if this word is in a prepositional noun phrase (B- prefix optional),
- iob      : BEGIN if the word marks the start of a new chunk,
INSIDE (optional) if the word is part of the previous chunk,
- custom   : a dictionary of (tag, value)-items for user-defined word tags.'

def append(self, word, lemma=None, type=None, chunk=None, role=None, relation=None, pnp=None, anchor=None, iob=None, custom={}):

    self._do_word(word, lemma, type)
    self._do_chunk(chunk, role, relation, iob)
    self._do_conjunction()
    self._do_relation()
    self._do_pnp(pnp, anchor)
    self._do_anchor(anchor)
    self._do_custom(custom)
