What happened?

When using mypy to check my code, I'm getting a spurious error. When passing a single string to get_axis_num, the return type is determined to be tuple[int, ...] instead of int.

What did you expect to happen?

I expected the return type to be int when passing a single single.

Minimal Complete Verifiable Example

# Note: to be run through mypy
import xarray as xr

def foo(x: xr.DataArray) -> None:
    reveal_type(x.get_axis_num("time"))

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

# Output from mypy
test.py:4: note: Revealed type is "builtins.tuple[builtins.int, ...]"
Success: no issues found in 1 source file

Anything else we need to know?

From a quick look at the code, I'm guessing this is because str is iterable and so is matching the first @overload.

Environment