chronos/src/main/java/com/redmadrobot/chronos/ChronosListener.java
public final boolean cancel(@NonNull final String tag, final boolean mayInterrupt) {
        final Integer id = mTaggedRequests.get(tag);
        //noinspection SimplifiableIfStatement
        if (id != null) {
            return cancel(id, mayInterrupt);
        } else {
            return false;
        }
    }
public final boolean cancel(@NonNull final String tag, final boolean mayInterrupt) {
        final Integer id = mTaggedRequests.get(tag);
        //noinspection SimplifiableIfStatement
        if (id != null) {
            return cancel(id, mayInterrupt);
        } else {
            return false;
        }
    }
Cancels operation launch by its tag. May not physically kill the background thread, but it is
guaranteed that the result of the operation will not be delivered to any ServiceConnector.

@param tag          a pre-cache key of the operation launch that should be cancelled
@param mayInterrupt {@code true} if threads executing operations task should be interrupted;
otherwise, in-progress tasks are allowed to complete
@return {@code false} if the task could not be cancelled, typically because it has already
completed normally or there is no running operation with a given tag; {@code true} otherwise
@see #invoke(ChronosOperation, boolean)
@see #invoke(ChronosOperation, String, boolean)
@see #cancel(int, boolean)
@see Chronos#cancelAll(boolean)