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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def complete(self):
 """ Return list of valid completions Returns a list of valid completions on the current level in the tree. If an element of type 'value' is found, its complete callback function is called (if set). """


        comp = []
        for k, v in self.key.items():

            # if we have reached a value, try to fetch valid completions
            if v['type'] == 'value':
                if 'complete' in v:
                    comp += v['complete'](self.inp_cmd[-1])

            # otherwise, k is our valid completion
            else:
                comp.append(k)

        return comp