api.allTypes()
        .filter { type -> type.isPublic && apiSpec.isApi(type.sourceName) }
        .flatMap { type -> kotlinExtensionFunctionsFor(type, sinceSupplier) }
        .distinctBy(::signatureKey)


private
fun signatureKey(extension: KotlinExtensionFunction): List<Any> = extension.run {
    listOf(targetType.sourceName, name) +
        parameters.flatMap { apiTypeKey(it.type) }
}


private

     */
    private PacMac() {
        // Utility class
    }

    /**
     *
     */
    private static final String HMAC_KEY = "HMAC";
    private static final byte[] MD5_CONSTANT = "signaturekey\0".getBytes(StandardCharsets.US_ASCII);
    private static final byte[] ZERO_IV = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    /**
     * Calculates a MAC using the ARCFOUR-HMAC-MD5 algorithm.

    *   Add 5D support to `SLICE` op.
    *   TFLite Supports SingatureDef:
        *   TFLiteConverter exports models with SignatureDef
        *   Interpreter supports getting a list of signatures and getting
            callable function for a given signaturedef.
    *   Add int8 support for `ReshapeV2`.
    *   Add experimental support for optimization with sparsity.