my class A { method foo { 'yes' } }
my class B { method foo { 'yes' } }
my class C is A is B { method foo { callsame } }
my class D is A { method foo { 'no' } }
my class E is C is D { method foo { callsame } }

L(A) := [A]
L(B) := [B]
L(C) := [C] + merge(L(A), L(B), [A, B])
      = [C] + merge([A], [B], [A, B])
      = [C, A] + merge([B], [B])
      = [C, A, B]
L(D) := [D] + merge(L(A), [A])
      = [D] + merge([A], [A])
      = [D, A]
L(E) := [E] + merge(L(C),L(D), [C, D])
      = [E] + merge([C, A, B], [D, A], [C, D])
      = [E, C] + merge([A, B], [D, A], [D])
      = [E, C, D] + merge([A, B], [A])
      = [E, C, D, A] + merge([B])
      = [E, C, D, A, B]