whole_func_string: function stdopts (opts) {
    opts = opts || {}
    opts.keys = opts.keys !== false // default keys to true
    opts.values = opts.values !== false // default values to true
    return opts
  }
func_code_string: function stdopts (opts) {
    opts = opts || {}
    opts.keys = opts.keys !== false // default keys to true
    opts.values = opts.values !== false // default values to true
    return opts
  }
func_documentation_string: opts standardized to work like levelup api