code: def p_path_expr_4(p):
      'PathExpr : FilterExpr DOUBLESLASH RelativeLocationPath'
      p[0] = [p[1]]
      p[0].append(_expand_double_slash())
      p[0].extend(p[3]f p_path_expr_4(p):
      'PathExpr : FilterExpr DOUBLESLASH RelativeLocationPath'
      p[0] = [p[1]]
      p[0].append(_expand_double_slash())
      p[0].extend(p[3])
docs: PathExpr : FilterExpr DOUBLESLASH RelativeLocationPath