human
Solve the following python programming problem given the following code:
@ classmethod 
def authenticate_by_password(cls, params) : 
    ' Authenticate user with login and password from :params:

        Used both by Token and Ticket-based auths (called from views).
        ' 
    def verify_password(user, password) : 
        return crypt.check (user.password, password) 
success = False 
    user = None 
    login = params ['login'].lower ().strip () 
    key = ('email' if ('@' in login) else 'username') 
    try : 
        user = cls.get_item (** { 
            key : login, 
}) 
except Exception as ex : 
        log.error (str (user)) 
if user : 
        password = params.get ('password', None) 
        success = (password and verify_password (user, password)) 
return (success, user) 

    
    

    Fix the buggy line: log.error (str (user))
assistant
#Here is Python program to fix the buggy line: log.

log.error (str (ex))