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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 as_knock(self, created=False):
 """ Returns a dictionary with the knock data built from _knocker_data """

        knock = {}
        if self.should_knock(created):
            for field, data in self._retrieve_data(None, self._knocker_data):
                knock[field] = data
        return knock