@Override
    public TensorType getType(String reference) {
        throw new UnsupportedOperationException("Not able to parse general references from string form");
    }
Returns the value of a simple variable name.

@param name the name of the variable whose value to return.
@return the value of the named variable.
searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java