What is the difference about ctrl.set(fn, clear=True), ctrl.set(fu) and ctrl.add(fn, clear=True)

[MountainAndMorning]

I think all of the three function calls would replace the older fn with the new one. I know it is wrong, but I do not understand its difference. Especially, If we call ctrl.set(fu) without clear, what happened about the older fn.

[jourdain]

@ctrl.set("name")
def fn_0():
  print("fn_0")


@ctrl.set("name")
def fn_1():
  print("fn_1")

ctrl.name() # => fn_1

---

@ctrl.set("name")
def fn_0():
  print("fn_0")

@ctrl.add("name")
def fn_2():
  print("fn_2")

@ctrl.set("name")
def fn_1():
  print("fn_1")

ctrl.name() # => fn_1, fn_2

---

@ctrl.set("name")
def fn_0():
  print("fn_0")

@ctrl.add("name")
def fn_2():
  print("fn_2")

ctrl.name() # => fn_0, fn_2

---

@ctrl.set("name")
def fn_0():
  print("fn_0")

@ctrl.add("name", clear=True)
def fn_2():
  print("fn_2")

ctrl.name() # => fn_2

---

@ctrl.add("name")
def fn_2():
  print("fn_2")

@ctrl.set("name")
def fn_0():
  print("fn_0")

ctrl.name() # => fn_0, fn_2

---

@ctrl.add("name")
def fn_2():
  print("fn_2")

@ctrl.set("name", clear=True)
def fn_0():
  print("fn_0")

ctrl.name() # => fn_0