### SUMMARY

Update validate-modules to report messages using named error codes like `version-added` instead of error numbers like `E305`.

This would match the behavior of other tools we use, such as pylint, which have one named error code per rule. This will also make ignore entries much easier to read.

Doing this before 2.9 is released will avoid potential backwards compatibility issues with ignore entries in collections.

##### ISSUE TYPE

Feature Idea

##### COMPONENT NAME

validate-modules

except Exception:
                    pass
                if not mainchecked:
                    self.reporter.error(
                        path=self.object_path,
                        code=109,
                        msg='Next to last line should be: if __name__ == "__main__":',
                        line=child.lineno
                    )
            
            if isinstance(child, ast.Expr):
                if isinstance(child.value, ast.Call):
                    if (isinstance(child.value.func, ast.Name) and
                            child.value.func.id == look_for):
                        lineno = child.lineno
                        if lineno < self.length - 1:
                            self.reporter.error(
                                path=self.object_path,
                                code=104,
                                msg=('Call to %s() not the last line' % look_for),
                                line=lineno
                            )
        if not lineno:
            self.reporter.error(
                path=self.object_path,
                code=103,
                msg=('Did not find a call to %s()' % look_for)
            )
        return lineno or 0
    def _find_has_import(self):