human
Solve the following python programming problem given the following code:
def _init_toolkit() : 
    ' Initialise the current toolkit. ' 
    def import_toolkit(tk) : 
        try : 
            be = ('pyface.ui.%s.' % tk) 
            __import__ ((be + 'init')) 
except : 
            raise 
return be 
if ETSConfig.toolkit : 
        be = import_toolkit (ETSConfig.toolkit) 
else : 
        known_toolkits = ('qt4', 'wx', 'null') 
        for tk in known_toolkits : 
            try : 
                with provisional_toolkit (tk) : 
                    be = import_toolkit (tk) 
break 
except ImportError as exc : 
                msg = "Could not import Pyface backend '{0}'" 
                logger.info (msg.format (tk)) 
                if (logger.getEffectiveLevel () <= logging.INFO) : 
                    logger.exception (exc) 
else : 
            try : 
                be = import_toolkit ('null') 
                import warnings 
                msg = ("Unable to import the '{0}' backend for pyface.
" + "using the 'null' backend instead.") 
                warnings.warn (msg.format (toolkit_name), RuntimeWarning) 
except ImportError as exc : 
                logger.exception (tk) 
                raise ImportError (('Unable to import a pyface backend for any of the %s toolkits' % ', '.join (known_toolkits))) 
global _toolkit_backend 
    _toolkit_backend = be 

    
    

    Fix the buggy line: logger.exception (tk)
assistant
#Here is Python program to fix the buggy line: logger.

logger.exception (exc)