# File lib/rmail/header.rb, line 156
    def replace(other)
      unless other.kind_of?(RMail::Header)
        raise TypeError, "#{other.class.to_s} is not of type RMail::Header"
      end
      temp = other.dup
      @fields = temp.fields
      @mbox_from = temp.mbox_from
      self
    end