old_contents: import sys
  from ezdxf.lldxf.validator import is_dxf_file
  from ezdxf.filemanagement import dxf_file_info
  
  
  def load_comments(stream):
      line = 1
      while True:
          try:
              code = stream.readline()
              value = stream.readline()
          except EOFError:
              return
          if code and value:  # StringIO(): empty strings indicates EOF
              try:
                  code = int(code)
              except ValueError:
                  raise ValueError('Invalid group code "{}" at line {}.'.format(code, line))
              else:
                  if code == 999:  # just yield comments
                      yield value
                  line += 2
          else:
              return
  
  
  def open_stream(filename):
      if is_dxf_file(filename):
          info = dxf_file_info(filename)
          return open(filename, mode='rt', encoding=info.encoding)
  
  
  if __name__ == '__main__':
      filename = sys.argv[1]
      stream = open_stream(filename)
      try:
          for comment in load_comments(stream):
              print(comment)
      finally:
          stream.close()
  
new_contents: import sys
  from ezdxf.lldxf.validator import is_dxf_file
  from ezdxf.filemanagement import dxf_file_info
  
  
  def load_comments(stream):
      line = 1
      while True:
          try:
              code = stream.readline()
              value = stream.readline()
          except EOFError:
              return
          if code and value:  # StringIO(): empty strings indicates EOF
              try:
                  code = int(code)
              except ValueError:
                  raise ValueError('Invalid group code "{}" at line {}.'.format(code, line))
              else:
                  if code == 999:  # just yield comments
                      yield value.rstrip('\n')
                  line += 2
          else:
              return
  
  
  def open_stream(filename):
      if is_dxf_file(filename):
          info = dxf_file_info(filename)
          return open(filename, mode='rt', encoding=info.encoding)
  
  
  if __name__ == '__main__':
      filename = sys.argv[1]
      stream = open_stream(filename)
      try:
          for comment in load_comments(stream):
              print(comment)
      finally:
          stream.close()
  
subject: remove newline from comment