class_docstr: Write records in the following format for a single record event_str:
  uint64 len(event_str)
  uint32 masked crc of len(event_str)
  byte event_str
  uint32 masked crc of event_str
  The implementation is ported from
  https://github.com/tensorflow/tensorflow/blob/master/tensorflow/core/lib/io/record_writer.cc
  Here we simply define a byte string _dest to buffer the record to be written to files.
  The flush and close mechanism is totally controlled in this class.
  In TensorFlow, _dest is a object instance of ZlibOutputBuffer (C++) which has its own flush
  and close mechanism defined.
code: def __init__(self, path):
      self._writer = None
      try:
          self._writer = open(path, "wb")
      except (OSError, IOError) as err:
          raise ValueError(
              "failed to open file {}: {}".format(path, str(err))
          )
  
file_path: mxboard/python/mxboard/record_writer.py
imports: from __future__ import absolute_import
  import struct
  from ._crc32c import crc32c
label_desc: Use image node_id 1 to create a new RecordWriter object from inherited base classes: object with example: obj = RecordWriter(path)