class_docstr: Represents positions in a target sentence. Used to keep track of
  which slot (position) is occupied.
docstr: :return: Mark slot at ``position`` as occupied
docstr_tok: [":","return",":","Mark","slot","at","``","position","``","as","occupied"]
code: def occupy(self, position):
      """
      :return: Mark slot at ``position`` as occupied
      """
      self._slots[position] = True
  
imports: import warnings
  from collections import defaultdict
  from math import factorial
  from nltk.translate import AlignedSent, Alignment, IBMModel, IBMModel4
  from nltk.translate.ibm_model import Counts, longest_target_sentence_length
label_desc: Use image node_id 2 for calling the Slots obj's underlying member method code with example usage: obj.occupy(position) without return types