public CallStack remove(Call call) {
        for (ListIterator<Call> i = iterator(); i.hasNext();) {
            Call current = i.next();
            if (current == call) {
                i.remove();
            }
        }
        return this;
    }
Removes the given call. Does nothing if the call is not present.

@param call
           the call to remove
@return this for convenience
docproc/src/main/java/com/yahoo/docproc/CallStack.java