class_docstr: Benchmark writer class.
  
  It writes benchmark statistics taken by :class:`FunctionBenchmark`
  in .ini file format. As it's not so readable,
  use :class:`FunctionBenchmarkCsvWriter` instead.
  
  Args:
      file (Python file object): The benchmark will be written to the file.
class_docstr_tok: ["Benchmark","writer","class",".","It","writes","benchmark","statistics","taken","by",":","class",":","`","FunctionBenchmark","`","in",".ini","file","format",".","As","it","'s","not","so","readable",",","use",":","class",":","`","FunctionBenchmarkCsvWriter","`","instead",".","Args",":","file","(","Python","file","object",")",":","The","benchmark","will","be","written","to","the","file","."]
docstr: Writing header function that is called at initialization.
          
docstr_tok: ["Writing","header","function","that","is","called","at","initialization","."]
code: def write_header(self):
      """Writing header function that is called at initialization."""
      pass
  
imports: from __future__ import print_function
  import nnabla
  import nnabla.initializer
  import sys
  import importlib
  import time
  from collections import namedtuple
  import csv
label_desc: Use image node_id 2 for calling the FunctionBenchmarkWriter obj's underlying member method code with example usage: obj.write_header() without return types