docstr: Don't call this directly. Use dataset.writer() instead.
code: def __init__(self, content):
      """Don't call this directly. Use dataset.writer() instead."""
      self._content = content
      self.mutex = None
  
imports: from caffe2.python import core, workspace
  from caffe2.python.dataio import Reader, Writer
  from caffe2.python.schema import Struct, from_blob_list, from_column_list, InitEmptyRecord
  import numpy
label_desc: Use image node_id 1 to create a new _DatasetWriter object from inherited base classes: Writer with example: obj = _DatasetWriter(content)