code: def __missing__(self, key):
      if key in self.safe:
          self[key] = chr(key)
      else:
          self[key] = "={:02X}".format(key)
      return self[key]
  
file_path: cpython/Lib/email/_encoded_words.py
imports: import re
  import base64
  import binascii
  import functools
  from string import ascii_letters, digits
  from email import errors
label_desc: Use image node_id 1 for calling the _QByteMap obj's underlying member method code with example usage: obj.__missing__(key) and returns: self