issues: 617140674

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
617140674 MDU6SXNzdWU2MTcxNDA2NzQ= 4054 Type checking fails for multiplication 37403847 closed 0     6 2020-05-13T04:55:14Z 2021-04-14T15:59:59Z 2021-04-14T15:59:59Z CONTRIBUTOR      

MCVE Code Sample

I save the following in a file called "foo.py" ```python import xarray as xr

def mul(x: float, y: xr.Dataset): return x*y

and run mypy foo.py ```

Expected Output

This should give Success: no issues found in 1 source file

Problem Description

Instead I get the output foo.py:4: error: Unsupported operand types for * ("float" and "Dataset") It gives a similar error for addition. If I reverse the order of multiplication it works as expected, namely ```python import xarray as xr

def mul(x: float, y: xr.Dataset): return y*x

gives Success: no issues found in 1 source file ```

But it would be nice if it also worked when the float is first, so I don't have to change a lot existing code to get typechecking to work.

Versions

I tested on version 0.15.1 and on the current master

Output of <tt>xr.show_versions()</tt> INSTALLED VERSIONS ------------------ commit: None python: 3.8.2 (default, May 7 2020, 20:00:49) [GCC 7.3.0] python-bits: 64 OS: Linux OS-release: 5.4.0-29-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8 libhdf5: None libnetcdf: None xarray: 0.15.2.dev61+gbd84186a pandas: 1.0.3 numpy: 1.18.4 scipy: None netCDF4: None pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: None nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: None distributed: None matplotlib: None cartopy: None seaborn: None numbagg: None pint: None setuptools: 46.2.0.post20200511 pip: 20.0.2 conda: None pytest: None IPython: None sphinx: None 
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