def add_journal_line(params = {})
      journal_line = nil
      case params
        when Hash 			 then  journal_line = JournalLine.new(params)
        when JournalLine then  journal_line = params
        else             raise InvalidLineItemError
      end
      @journal_lines << journal_line
      journal_line
    end
def add_journal_line(params = {})
      journal_line = nil
      case params
        when Hash 			 then  journal_line = JournalLine.new(params)
        when JournalLine then  journal_line = params
        else             raise InvalidLineItemError
      end
      @journal_lines << journal_line
      journal_line
    end
from_xml