def format_headers(headers)
      return headers.map do |k, v|
        v = REDACTED_STR if k == 'Authorization'
        [k, v].join(': ')
      end.join(', ')
    end
def format_headers(headers)
      return headers.map do |k, v|
        v = REDACTED_STR if k == 'Authorization'
        [k, v].join(': ')
      end.join(', ')
    end
Format headers, redacting sensitive information.