code: def _read_tuple_block(self, stream):
      line = stream.readline().strip()
      if line:
          return [tuple(line.split(self._delimiter, 1))]
      else:
          return []
  
imports: from nltk.corpus.reader.api import *
  from nltk.corpus.reader.util import *
label_desc: Use image node_id 3 for calling the StringCategoryCorpusReader obj's underlying member method code with example usage: obj._read_tuple_block(stream) and returns: list, list