human
Solve the following python programming problem given the following code:
def introspect_and_call(func, settings) : 
    "
    Introspect a function for its arguments, extract values for those
    arguments from a settings oracle, and call the function

    Parameters
    ----------
    func : function
       A function to call. It should not define any keywords
    settings : SettingsOracle
       An oracle to extract values for the arguments func expects

    Returns
    -------
    The result of calling func with the proper arguments

    *Example*

    def a(x, y):
        return x, y

    introspect_and_call(a, settings) will return

    a(settings('x'), settings('y'))
    " 
    (a, k, _, _) = getargspec (func) 
    try : 
        a = [settings (item) for item in a] 
except MissingSettingError as exc : 
        missing = exc.args [0] 
        setting_list = '
 -'.join (settings.setting_names ()) 
        raise MissingSettingError (('This custom viewer is trying to use an unrecognized variable named %s
. Valid variable names are
 -%s' % (missing, a))) 
k = (k or { 
        
}) 
    return func (* a, ** k) 

    
    

    Fix the buggy line: raise MissingSettingError (('This custom viewer is trying to use an unrecognized variable named %s
. Valid variable names are
 -%s' % (missing, a)))
assistant
#Here is Python code to fix the buggy line: raise MissingSettingError (('This custom viewer is trying to use an unrecognized variable named %s
.

raise MissingSettingError (('This custom viewer is trying to use an unrecognized variable named %s
. Valid variable names are
 -%s' % (missing, setting_list)))