    # File lib/rmail/mailbox/mboxreader.rb, line 61
          def initialize(input, line_separator = $/)
            super(input)
            @end_of_message = false
            @chunk_minsize = 0
            @sep = line_separator
            @tail = nil

            # This regexp will match a From_ header, or some prefix.
            re_string = RMail::Parser::PushbackReader.
              maybe_contains_re("#{@sep}From ")
            @partial_from_re = Regexp.new(re_string)

            # This regexp will match an entire From_ header.
            @entire_from_re = /\A#{@sep}From .*?#{@sep}/
          end