def _get_field(self, extras, field, default=None):
long_f = '<STR_LIT>'.format(field)<EOL>if long_f in extras:<EOL><INDENT>return extras[long_f]<EOL><DEDENT>else:<EOL><INDENT>self.log.info('<STR_LIT>', field)<EOL>return default<EOL><DEDENT>
Fetches a field from extras, and returns it. This is some Airflow
magic. The google_cloud_platform hook type adds custom UI elements
to the hook page, which allow admins to specify service_account,
key_path, etc. They get formatted as shown below.