human
Solve the following python programming problem given the following code:
def escape(self, string) : 
    def cb(match) : 
        esc = match.group (1) 
        if (esc == '\\') : 
            return '\\\\' 
else : 
            if (esc == '
') : 
                return '\
' 
else : 
                if (esc == '|') : 
                    return '\\_' 
else : 
                    assert 0 
return re.sub ('(\\\\|\
|\\|)', self, string) 

    
    

    Fix the buggy line: return re.sub ('(\\\\|\
|\\|)', self, string)
assistant
#Here is Python program to fix the buggy line: return re.

return re.sub ('(\\\\|\
|\\|)', def cb(, string)