Remove self from classes in How to add new backends docs

[Illviljan]

Copy pasting the examples in http://xarray.pydata.org/en/stable/internals/how-to-add-new-backend.html resulted in crashes. Make the docs copy/paste friendly by removing the self arguments.

Example:

expected=xr.Dataset(
dict(a=2*np.arange(5)), coords=dict(x=("x", np.arange(5), dict(units="s")))
)
classCustomBackend(xr.backends.BackendEntrypoint):
defopen_dataset(
self,
filename_or_obj,
drop_variables=None,
**kwargs,
):
returnexpected.copy(deep=True)
xr.open_dataset("fake_filename", engine=CustomBackend)
TypeError: open_dataset() missing1requiredpositionalargument: 'filename_or_obj'

This works if self is removed:

expected=xr.Dataset(
dict(a=2*np.arange(5)), coords=dict(x=("x", np.arange(5), dict(units="s")))
)
classCustomBackend(xr.backends.BackendEntrypoint):
defopen_dataset(
filename_or_obj,
drop_variables=None,
**kwargs,
):
returnexpected.copy(deep=True)
xr.open_dataset("fake_filename", engine=CustomBackend)
<xarray.Dataset>Dimensions: (a: 5, x: 5)
Coordinates:
*a (a) int3202468*x (x) int3201234Datavariables:
*empty*

• Passes pre-commit run --all-files

[max-sixty]

Thank you again @Illviljan !

[github-actions]

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