Maybe spurious traceback on calling .format on a variable

[Lalufu]

While investingating some non-transformed files, I came across this case:

A = "foo.{bar}"


def foo(x):
    return A.format(x)

When running flynt on this in verbose mode, the following output appears:

Exception during conversion of code: Traceback (most recent call last):
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/transform.py", line 32, in transform_chunk
    converted, changed = fstringify_node(
                         ^^^^^^^^^^^^^^^^
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/FstringifyTransformer.py", line 88, in fstringify_node
    result = ft.visit(node)
             ^^^^^^^^^^^^^^
  File "/opt/blue-python/3.11/lib64/python3.11/ast.py", line 418, in visit
    return visitor(node)
           ^^^^^^^^^^^^^
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/FstringifyTransformer.py", line 31, in visit_Call
    result_node = joined_string(
                  ^^^^^^^^^^^^^^
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/format_call_transforms.py", line 18, in joined_string
    assert isinstance(fmt_call.func, ast.Attribute) and isinstance(
AssertionError
Traceback (most recent call last):
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/transform.py", line 32, in transform_chunk
    converted, changed = fstringify_node(
                         ^^^^^^^^^^^^^^^^
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/FstringifyTransformer.py", line 88, in fstringify_node
    result = ft.visit(node)
             ^^^^^^^^^^^^^^
  File "/opt/blue-python/3.11/lib64/python3.11/ast.py", line 418, in visit
    return visitor(node)
           ^^^^^^^^^^^^^
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/FstringifyTransformer.py", line 31, in visit_Call
    result_node = joined_string(
                  ^^^^^^^^^^^^^^
  File "~/venv/flynt/lib64/python3.11/site-packages/flynt/transform/format_call_transforms.py", line 18, in joined_string
    assert isinstance(fmt_call.func, ast.Attribute) and isinstance(
AssertionError
fstringifying ~/t.py...no change
Running flynt v.1.0.1
Using following options: Namespace(verbose=True, quiet=False, no_multiline=False, line_length=88, dry_run=True, stdout=False, string=False, transform_percent=True, transform_format=True, transform_concats=False, transform_joins=False, fail_on_change=False, aggressive=False, exclude=None, src=['./t.py'], version=False)
Running flynt in dry-run mode. No files will be changed.

Flynt run has finished. Stats:

Execution time:                            0.008s
Files checked:                             1
Files modified:                            0

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~ https://github.com/ikamensh/flynt ~
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I can see why this would not work, but the traceback looks maybe a bit more scary than it needs to be?