old_contents: class CondaEnvException(Exception):
      pass
  
  
  class EnvironmentFileNotFound(CondaEnvException):
      def __init__(self, filename, *args, **kwargs):
          msg = '{} file not found'.format(filename)
          self.filename = filename
          super(EnvironmentFileNotFound, self).__init__(msg, *args, **kwargs)
  
  
  class EnvironmentFileNotDownloaded(CondaEnvException):
      def __init__(self, filename, *args, **kwargs):
          msg = '{} file not downloaded'.format(filename)
          self.filename = filename
          super(EnvironmentFileNotDownloaded, self).__init__(msg, *args, **kwargs)
  
new_contents: class CondaEnvException(Exception):
      pass
  
  
  class EnvironmentFileNotFound(CondaEnvException):
      def __init__(self, filename, *args, **kwargs):
          msg = '{} file not found'.format(filename)
          self.filename = filename
          super(EnvironmentFileNotFound, self).__init__(msg, *args, **kwargs)
  
  
  class EnvironmentFileNotDownloaded(CondaEnvException):
      def __init__(self, username, packagename, *args, **kwargs):
          msg = '{}/{} file not downloaded'.format(username, packagename)
          self.username = username
          self.packagename = packagename
          super(EnvironmentFileNotDownloaded, self).__init__(msg, *args, **kwargs)
  
  
  class EnvironmentUsernameRequired(CondaEnvException):
      def __init__(self, *args, **kwargs):
          msg = 'Username is required'
          super(EnvironmentUsernameRequired, self).__init__(msg, *args, **kwargs)
  
  
  class PackageNotFound(CondaEnvException):
      def __init__(self, username, packagename, *args, **kwargs):
          msg = '{}/{} not found'.format(username, packagename)
          self.username = username
          self.packagename = packagename
          super(PackageNotFound, self).__init__(msg, *args, **kwargs)
  
subject: Add create --binstar exceptions