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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 mifare_classic_read_block(self, block_number):
 """Read a block of data from the card. Block number should be the block to read. If the block is successfully read a bytearray of length 16 with data starting at the specified block will be returned. If the block is not read then None will be returned. """

        # Send InDataExchange request to read block of MiFare data.
        response = self.call_function(PN532_COMMAND_INDATAEXCHANGE,
                                      params=[0x01, MIFARE_CMD_READ, block_number & 0xFF],
                                      response_length=17)
        # Check first response is 0x00 to show success.
        if response[0] != 0x00:
            return None
        # Return first 4 bytes since 16 bytes are always returned.
        return response[1:]