docs: function copyAndOffsetMapping(existingMapping) {
      var column     = getColumnAfter(existingMapping.generatedLine - 1, existingMapping.generatedColumn);
      var newMapping = {
        generated: {
          line  : existingMapping.generatedLine,
          column: column
        }
      };
      if (existingMapping.source) {
        newMapping.source   = existingMapping.source;
        newMapping.original = {
          line  : existingMapping.originalLine,
          column: existingMapping.originalColumn
        };
        if (existingMapping.name) {
          newMapping.name = existingMapping.name;
        }
      }
      generator.addMapping(newMapping);
    }