old_contents: import logging
  
  import click
  from .core import _normalize_logger
  
  
  def simple_verbosity_option(logger=None, *names, **kwargs):
      '''A decorator that adds a `--verbosity, -v` option to the decorated
      command.
  
      Name can be configured through ``*names``. Keyword arguments are passed to
      the underlying ``click.option`` decorator.
      '''
  
      if not names:
          names = ['--verbosity', '-v']
      if isinstance(logger, str) and logger.startswith('-'):
          raise ValueError('Since click-log 0.2.0, the first argument must now '
                           'be a logger.')
  
      kwargs.setdefault('default', 'INFO')
      kwargs.setdefault('metavar', 'LVL')
      kwargs.setdefault('expose_value', False)
      kwargs.setdefault('help', 'Either CRITICAL, ERROR, WARNING, INFO or DEBUG')
      kwargs.setdefault('is_eager', True)
  
      logger = _normalize_logger(logger)
  
      def decorator(f):
          def _set_level(ctx, param, value):
              x = getattr(logging, value.upper(), None)
              if x is None:
                  raise click.BadParameter(
                      'Must be CRITICAL, ERROR, WARNING, INFO or DEBUG, not {}'
                  )
              logger.setLevel(x)
  
          return click.option(*names, callback=_set_level, **kwargs)(f)
      return decorator
  
new_contents: import logging
  
  import click
  from .core import _normalize_logger
  
  
  def simple_verbosity_option(logger=None, *names, **kwargs):
      '''A decorator that adds a `--verbosity, -v` option to the decorated
      command.
  
      Name can be configured through ``*names``. Keyword arguments are passed to
      the underlying ``click.option`` decorator.
      '''
  
      if not names:
          names = ['--verbosity', '-v']
      if isinstance(logger, str) and logger.startswith('-'):
          raise ValueError('Since click-log 0.2.0, the first argument must now '
                           'be a logger.')
  
      kwargs.setdefault('default', 'INFO')
      kwargs.setdefault('metavar', 'LVL')
      kwargs.setdefault('expose_value', False)
      kwargs.setdefault('help', 'Either CRITICAL, ERROR, WARNING, INFO or DEBUG')
      kwargs.setdefault('is_eager', True)
  
      logger = _normalize_logger(logger)
  
      def decorator(f):
          def _set_level(ctx, param, value):
              x = getattr(logging, value.upper(), None)
              if x is None:
                  raise click.BadParameter(
                      'Must be CRITICAL, ERROR, WARNING, INFO or DEBUG, not {}'
                      .format(value)
                  )
              logger.setLevel(x)
  
          return click.option(*names, callback=_set_level, **kwargs)(f)
      return decorator
  
subject: Add missing string interpolation in error message. (#24)