__ridx__ is an _undefined name_ in this context but __self.ridx__ is used three other times in this method and nine times in this class. Undefined names may raise [NameError](https://docs.python.org/3/library/exceptions.html#NameError) at runtime.
flake8 testing of https://github.com/opencv/opencv
$ __flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics__
```
./modules/ts/misc/table_formatter.py:50:23: F821 undefined name 'ridx'
self.rows[ridx + 1].props = properties
^
```
if len(self.rows) - 1 == self.ridx:
self.rows.append(tblRow(len(self.columns), properties))
else:
- self.rows[ridx + 1].props = properties
+ self.rows[self.ridx + 1].props = properties
self.ridx += 1
return self.rows[self.ridx]