code: def dedent(self):
      assert self.indentlevel > 0
      self.indentlevel = self.indentlevel - 1
  
imports: from fontTools.misc.textTools import byteord, strjoin, tobytes, tostr
  import sys
  import os
  import string
label_desc: Use image node_id 17 for calling the XMLWriter obj's underlying member method code with example usage: obj.dedent() without return types