toUByteOrNull
Platform and version requirements: JVM (1.5), JS (1.5), Native (1.5) 
fun String.toUByteOrNull(): UByte?
Parses the string as an UByte number and returns the result or null if the string is not a valid representation of a number.
Platform and version requirements: JVM (1.5), JS (1.5), Native (1.5) 
fun String.toUByteOrNull(radix: Int): UByte?
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Licensed under the Apache License, Version 2.0.
    https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/to-u-byte-or-null.html