public default void addFrom(final Traversal.Admin<?, ?> fromTraversal) {
        throw new UnsupportedOperationException("The from()-modulating step does not support traversal-based modulation: " + this);
    }
FromToModulating are for {@link Step}s that support from()- and to()-modulation. This step is similar to
{@link ByModulating}.

@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/FromToModulating.java