class_docstr: :class:`.History` class that stores all strings in a file.
class_docstr_tok: [":","class",":","`",".History","`","class","that","stores","all","strings","in","a","file","."]
code: def append(self, string):
      self.strings.append(string)
  
      # Save to file.
      with open(self.filename, "ab") as f:
  
          def write(t):
              f.write(t.encode("utf-8"))
  
          write("\n# %s\n" % datetime.datetime.now())
          for line in string.split("\n"):
              write("+%s\n" % line)
  
imports: from __future__ import unicode_literals
  from abc import ABCMeta, abstractmethod
  from six import with_metaclass
  import datetime
  import os
label_desc: Use image node_id 3 for calling the FileHistory obj's underlying member method code with example usage: obj.append(string) without return types