old_contents: import gdb
  import sys
  
  
  class ConcatCommand(BaseCommand):
      """Executes a command and print concatenated results with a prefix."""
  
      def __init__(self):
          super(ConcatCommand, self).__init__("concat")
  
      def action(self, arg):
          pair = arg.partition(' ')
          sys.stdout.write(pair[0] + gdb.execute(pair[2], False, True))
  
  ConcatCommand()
  
new_contents: import gdb
  import sys
  
  
  class ConcatCommand(BaseCommand):
      """Executes a command and print concatenated results with a prefix."""
  
      def __init__(self):
          super(ConcatCommand, self).__init__("concat")
  
      def action(self, arg, from_tty):
          pair = arg.partition(' ')
          sys.stdout.write(pair[0] + gdb.execute(pair[2], False, True))
  
  ConcatCommand()
  
subject: fix arguments count