class_docstr: Basic storage unit of SentenceLDA documents, contains word ids
  of the sentence and its corresponding topic id.
class_docstr_tok: ["Basic","storage","unit","of","SentenceLDA","documents",",","contains","word","ids","of","the","sentence","and","its","corresponding","topic","id","."]
code: def __init__(self, topic, tokens):
      self.topic = topic
      self.tokens = tokens
  
imports: import numpy
label_desc: Use image node_id 1 to create a new Sentence object from inherited base classes: object with example: obj = Sentence(topic, tokens)