old_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  import argparse
  import json
  import os
  import sys
  
  from . import __VERSION__
  from .dialects import FormDialect, JSONDialect, YAMLDialect
  from .jsonform import encode
  
  
  class InvalidLiteralError(ValueError):
      def __init__(self, key, *args, **kwargs):
          self.key = key
          super(InvalidLiteralError, self).__init__(key, *args, **kwargs)
  
  
  def makepair(dialect, pair):
      """Return a (key, value) tuple from a KEY=VALUE formatted string.
      """
  
      parts = pair.split('=', 1)
      if len(parts) == 1:
          parts.append(None)
      key, value = parts
      if key[-1] == ":":
          key = key[:-1]
          try:
              value = dialect.from_literal(value)
          except ValueError:
              raise InvalidLiteralError(key)
      else:
          value = dialect.to_python(value)
      return key, value
  
  
  def fatal(msg, code=1):
      sys.stderr.write("{}: {}\n".format(os.path.basename(sys.argv[0]), msg))
      sys.exit(code)
  
  
  def main():
      ap = argparse.ArgumentParser(
          description="Shorthand encoding format syntax.", prog="jarg")
      dialects = ap.add_mutually_exclusive_group()
      dialects.add_argument(
          '-j', '--json', action='store_const', const=JSONDialect,
          dest='dialect', help="use the JSON dialect")
      dialects.add_argument(
          '-y', '--yaml', action='store_const', const=YAMLDialect,
          dest='dialect', help="use the YAML dialect")
      dialects.add_argument(
          '-f', '--form', action='store_const', const=FormDialect,
          dest='dialect', help="use the form encoding dialect")
      ap.add_argument(
          'pair', nargs='+', help="a pair in the format of KEY=VALUE")
      ap.add_argument(
          '-V', '--version', action='version',
          version="%(prog)s {}".format('.'.join(__VERSION__)))
      args = ap.parse_args()
  
      dialect = (args.dialect or JSONDialect)()
      if sys.stdin.isatty():
          context = {}
      else:
          context = dialect.from_literal(sys.stdin.read())
      try:
          context.update(encode(makepair(dialect, pair) for pair in args.pair))
      except InvalidLiteralError as e:
          fatal("valid literal value required for key `{}'".format(e.key))
      sys.stdout.write(dialect.dumps(context))
  
  if __name__ == '__main__':
      main()
  
new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  import argparse
  import os
  import sys
  
  from . import __VERSION__
  from .dialects import FormDialect, JSONDialect, YAMLDialect
  from .jsonform import encode
  
  
  class InvalidLiteralError(ValueError):
      def __init__(self, key, *args, **kwargs):
          self.key = key
          super(InvalidLiteralError, self).__init__(key, *args, **kwargs)
  
  
  def makepair(dialect, pair):
      """Return a (key, value) tuple from a KEY=VALUE formatted string.
      """
  
      parts = pair.split('=', 1)
      if len(parts) == 1:
          parts.append(None)
      key, value = parts
      if key[-1] == ":":
          key = key[:-1]
          try:
              value = dialect.from_literal(value)
          except ValueError:
              raise InvalidLiteralError(key)
      else:
          value = dialect.to_python(value)
      return key, value
  
  
  def fatal(msg, code=1):
      sys.stderr.write("{}: {}\n".format(os.path.basename(sys.argv[0]), msg))
      sys.exit(code)
  
  
  def main():
      ap = argparse.ArgumentParser(
          description="Shorthand encoding format syntax.", prog="jarg")
      dialects = ap.add_mutually_exclusive_group()
      dialects.add_argument(
          '-j', '--json', action='store_const', const=JSONDialect,
          dest='dialect', help="use the JSON dialect")
      dialects.add_argument(
          '-y', '--yaml', action='store_const', const=YAMLDialect,
          dest='dialect', help="use the YAML dialect")
      dialects.add_argument(
          '-f', '--form', action='store_const', const=FormDialect,
          dest='dialect', help="use the form encoding dialect")
      ap.add_argument(
          'pair', nargs='+', help="a pair in the format of KEY=VALUE")
      ap.add_argument(
          '-V', '--version', action='version',
          version="%(prog)s {}".format('.'.join(__VERSION__)))
      args = ap.parse_args()
  
      dialect = (args.dialect or JSONDialect)()
      if sys.stdin.isatty():
          context = {}
      else:
          context = dialect.from_literal(sys.stdin.read())
      try:
          context.update(encode(makepair(dialect, pair) for pair in args.pair))
      except InvalidLiteralError as e:
          fatal("valid literal value required for key `{}'".format(e.key))
      sys.stdout.write(dialect.dumps(context))
  
  if __name__ == '__main__':
      main()
  
subject: remove unused json import