print arches of oriented graph

from collections.abc import *
from functools import reduce

def print_arcs(graph: Mapping[Set]):

    def redFn1(acc, elem):
        def redFn2(acc2, elem2):
            print(f"{elem}->{elem2}")
        reduce(redFn2, graph[elem], None)
    reduce(redFn1, graph, None)


g = {
    'a': {'b', 'c', 'c'},
    'ef': {'c'},
    'c': {'b'}
}
print_arcs(g)