Generator: fixed a problem with the root function/operator.
Generator: fixed a problem with the root function/operator.

nickerso/libcellml,hsorby/libcellml,nickerso/libcellml,cellml/libcellml,cellml/libcellml,hsorby/libcellml,hsorby/libcellml,cellml/libcellml,nickerso/libcellml,hsorby/libcellml,nickerso/libcellml,cellml/libcellml