code: def _diff_violations(self):
          
          if not self._diff_violations_dict:
              self._diff_violations_dict = {
                      src_path: DiffViolations(
                          self._violations.violations(src_path),
                          self._violations.measured_lines(src_path),
                          self._diff.lines_changed(src_path),
                      )
                   for src_path in self._diff.src_paths_changed()
              }
          return self._diff_violations_dict
docs: Returns a dictionary of the form:
  
              { SRC_PATH: DiffViolations(SRC_PATH) }
  
          where `SRC_PATH` is the path to the source file.
  
          To make this efficient, we cache and reuse the result.