public static Value of(Tensor tensor) {
        return new TensorValue(tensor);
    }
Parses the given string to a value and returns it.
Different subtypes of Value will be returned depending on the string.

@return a mutable Value
@throws IllegalArgumentException if the given string is not parseable as a value
searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Value.java