public DataType setInputType(DataType inputType, TypeContext context) {
        return assignInputType(inputType);
    }
Sets the input type of this and returns the resulting output type, or null if it cannot be
uniquely determined.
Subtypes may implement this by calling setInputType(inputType, requiredType, VerificationContext context).
indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/Expression.java