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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 sign_item(encrypted_item, signing_key, crypto_config):
 # type: (dynamodb_types.ITEM, DelegatedKey, CryptoConfig) -> dynamodb_types.BINARY_ATTRIBUTE """Generate the signature DynamoDB atttribute. :param dict encrypted_item: Encrypted DynamoDB item :param DelegatedKey signing_key: DelegatedKey to use to calculate the signature :param CryptoConfig crypto_config: Cryptographic configuration :returns: Item signature DynamoDB attribute value :rtype: dict """

    signature = signing_key.sign(
        algorithm=signing_key.algorithm,
        data=_string_to_sign(
            item=encrypted_item,
            table_name=crypto_config.encryption_context.table_name,
            attribute_actions=crypto_config.attribute_actions,
        ),
    )
    return {Tag.BINARY.dynamodb_tag: signature}