human
Solve the following python programming problem given the following code:
def unpickle(self, fgraph) : 
    def get_destroyers_of(r) : 
        (droot, impact, root_destroyer) = self.refresh_droot_impact () 
        try : 
            return [root_destroyer [droot [r]]] 
except Exception : 
            return [] 
fgraph.destroyers = <MASK> 
    
    Given the code above, what is a proper replacement for <MASK>? Choose among: fgraph, self
assistant
#Here is a proper replacement for <MASK>.
def get_destroyers_of(