public static IllegalArgumentException couldNotLocatePathFromLabel(final String fromLabel) {
            return new IllegalArgumentException("Could not locate path from-label: " + fromLabel);
        }
Isolate a sub-path from the path object. The isolation is based solely on the path labels.
The to-label is inclusive. Thus, from "b" to "c" would isolate the example path as follows {@code a,[b,c],d}.
Note that if there are multiple path segments with the same label, then its the last occurrence that is isolated.
For instance, from "b" to "c" would be {@code a,b,[b,c,d,c]}.

@param fromLabel The label to start recording the sub-path from.
@param toLabel   The label to end recording the sub-path to.
@return the isolated sub-path.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/Path.java