Net::HTTPHeader#append_field_value

# File tmp/rubies/ruby-3.4.1/lib/net/http/header.rb, line 285
        def append_field_value(ary, val)
  case val
  when Enumerable
    val.each{|x| append_field_value(ary, x)}
  else
    val = val.to_s
    if /[\r\n]/n.match?(val.b)
      raise ArgumentError, 'header field value cannot include CR/LF'
    end
    ary.push val
  end
end