code: def __iter__(self):
      begin = self.begin
      with open(self.fname) as f:
          for line in f:
              line = list(line)
              if begin:
                  line = [begin] + line
              yield line
  
file_path: dynet/examples/python-utils/util.py
imports: import mmap
label_desc: Use image node_id 2 for calling the CharsCorpusReader obj's underlying member method code with example usage: obj.__iter__() without return types