text: class Buffer:
  
      def __init__(self, file_name=None):
          if file_name is None:
              self.lines = [ "\n" ]
          else:
              self.file_name = file_name
              with open(file_name, "r") as f:
                  self.lines = []
                  for line in f:
                      self.lines.append(line)
  