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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 _concat(self, data):
 """ Concatenate and slice the accepted data types to the defined length. """

        if isinstance(data, np.ndarray):
            data_length = len(data)
            if data_length < self.length:
                prev_chunk = self.data[-(self.length-data_length):]
                data = np.concatenate([prev_chunk, data])
            elif data_length > self.length:
                data = data[-self.length:]
        elif util.pd and isinstance(data, util.pd.DataFrame):
            data_length = len(data)
            if data_length < self.length:
                prev_chunk = self.data.iloc[-(self.length-data_length):]
                data = util.pd.concat([prev_chunk, data])
            elif data_length > self.length:
                data = data.iloc[-self.length:]
        elif isinstance(data, dict) and data:
            data_length = len(list(data.values())[0])
            new_data = {}
            for k, v in data.items():
                if data_length < self.length:
                    prev_chunk = self.data[k][-(self.length-data_length):]
                    new_data[k] = np.concatenate([prev_chunk, v])
                elif data_length > self.length:
                    new_data[k] = v[-self.length:]
                else:
                    new_data[k] = v
            data = new_data
        self._chunk_length = data_length
        return data