# File lib/mail/encodings/encodings.rb, line 146
    def Encodings.b_value_encode(str, encoding = nil)
      string, encoding = RubyVer.b_value_encode(str, encoding)
      string.split("\n").map do |str|
        "=?#{encoding}?B?#{str.chomp}?="
      end.join(" ")
    end