15 lines
222 B
Python
15 lines
222 B
Python
|
def add(m, k, v):
|
||
|
|
s = m.get(k)
|
||
|
|
if s is None:
|
||
|
|
s = set()
|
||
|
|
m[k] = s
|
||
|
|
s.add(v)
|
||
|
|
|
||
|
|
def discard(m, k, v):
|
||
|
|
s = m.get(k)
|
||
|
|
if s is None:
|
||
|
|
return
|
||
|
|
s.discard(v)
|
||
|
|
if not s:
|
||
|
|
m.pop(k)
|