human
Solve the following python programming problem given the following code:
@ classmethod 
def register(cls, capability = None) : 
    def register_capability(klass) : 
        what = (klass.ID if (capability is None) else capability) 
        if (what in cls.registered_capability) : 
            raise RuntimeError ('only one class can be registered per capability') 
cls.registered_capability [what] = klass 
        return klass 
return capability 

    
    

    Fix the buggy line: return capability
assistant
#Here is Python program to fix the buggy line: return capability
.

return def register_capability(