code: def write_config(data, conf_dir=DEFAULT_CONFIG_DIR, codec="yaml",
                   backup_existing=False):
      
      if not codec:
          codec = 'yaml'
      codec = munge.get_codec(codec)()
      conf_dir = os.path.expanduser(conf_dir)
      if not os.path.exists(conf_dir):
          os.mkdir(conf_dir)
  
      # Check for existing file, back up if necessary
      outpath = os.path.join(conf_dir, 'config.' + codec.extensions[0])
      if backup_existing and os.path.exists(outpath):
          os.rename(outpath, outpath + '.bak')
      codec.dump(data, open(outpath, 'w'))
docs: Write config values to a file.
  
      Arguments:
          - conf_dir<str>: path to output directory
          - codec<str>: output field format
          - backup_existing<bool>: if a config file exists,
              make a copy before overwriting