How to implement "exclusive gateway" in dask graphs?

My goal is to write a workflow framework using dask graph.
Both serial and parallel tasks work well.
But when I encounter an exclusive gateway element, I don’t know how to implement it.
I have a crude version here.

# task graphs。  a  |-on_success-> b   means:  a -> b or a -> c
                               |-on_error->   c
def a(n):
        n = 1/n
    except Exception as e:
        return 'error', 0
    return 'success', n

def b(n):
    print('b', n)

def c(n):
    print('c', n)

def func_condition(ret, branch):

if __name__ == '__main__':
    client = Client('xx:8786')
    dsk = {
            'a': (a, 0),
            'z': (func_condition, 'a', {'success':b, 'error':c}),
    print(client.get(dsk, 'z'))

The above can simply meet the demand.

But if there is more path depth in the branch?

a -> b -> d or a -> c -> e

Is there a better way to achieve it?