def __add__(self, Other: Union[PySequence, Var]) -> PySequence:
Other_EoT = Other.unification_chain_end()
# If not, can't append.
assert isinstance(Other_EoT, PySequence)
Result = Var()
for _ in append(self, Other_EoT, Result):
Result_EoT = Result.unification_chain_end()
# To make the PyCharm type checker happy.
assert isinstance(Result_EoT, PySequence)
return Result_EoT
"""
print(
f'\n?- LinkedList([Var()]).is_instantiated(): {LinkedList([Var( )]).is_instantiated( )}'
)
A = LinkedList([1, 2, 3])
B_Head = Var()
B_Tail = Var()
B = LinkedList(B_Head, B_Tail)
print(f'1. A: {A}, B: {B}')
for _ in unify(A, B):
print(f'2. A: {A}, B: {B}')
B_Tail_TrailEnd = B_Tail.unification_chain_end()
C = LinkedList([0, *B_Tail_TrailEnd.get_py_value()])
print(f'3. C: {C}')
D2 = Var()
D3 = Var()
D = LinkedList([D3, D2, D3])
print(f'4a. B: {B}, D: {D}')
for _ in unify(D.tail(), B.tail()):
print(f'4b. unify(D.tail(), B.tail() => B: {B}, D: {D}')
for _ in unify(D.head(), B):
print(f'4c. unify(D.head(), B) => B: {B}, D: {D}')
E = Var()
print(f'5a. B: {B}, E: {E}')
for _ in unify(E, B):