class_docstr: an OpenType subtable (%s) had a format I didn't expect
code: def reason(self):
      s = self.__doc__ % self.cause["subtable"]
      if "value" in self.cause:
          s += f" ({self.cause['value']!r})"
      return s
  
imports: import textwrap
label_desc: Use image node_id 2 for calling the UnsupportedFormat obj's underlying member method code with example usage: obj.reason() and returns: s