This seems a little too easy, but the PR just adds lshift and rshit to generate_ops.py and ops.py then generated the 2 stub files with generate_ops.py.

• [x] Closes #7727
• [x] Tests added for:
• xr.Variable
• DataArray
• dask
• groupby
• [x] User visible changes (including notable bug fixes) are documented in whats-new.rst
• There will be new << >> syntax for dataarrays and datasets.
• [x] New functions/methods are listed in api.rst
  • Existing basic math operators aren't really listed, that I can find.
  • Could add example code in the "Data arrays also implement many numpy.ndarray methods:" section of computation.rst ?

I'll wait for initial review before spending time on whats-new and api docs.

This enables bit shifting on arrays (when the type supports it).

```python import xarray as xr

x = xr.DataArray(5) print(x << 1)

<xarray.DataArray ()>

array(10)

x = xr.DataArray([0,1,2,3,4,5]) print(x << 1)

<xarray.DataArray (dim_0: 6)>

array([ 0, 2, 4, 6, 8, 10])

Dimensions without coordinates: dim_0

x = xr.DataArray([0,1,2,3,4,5]) print(x >> 1)

<xarray.DataArray (dim_0: 6)>

array([0, 0, 1, 1, 2, 2])

Dimensions without coordinates: dim_0

x = xr.DataArray([0,1,2,3,4,5.]) print(x >> 1) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/workspaces/xarray/xarray/core/_typed_ops.py", line 255, in rshift return self._binary_op(other, operator.rshift) File "/workspaces/xarray/xarray/core/dataarray.py", line 4566, in _binary_op f(self.variable, other_variable) File "/workspaces/xarray/xarray/core/_typed_ops.py", line 461, in rshift return self._binary_op(other, operator.rshift) File "/workspaces/xarray/xarray/core/variable.py", line 2662, in _binary_op f(self_data, other_data) if not reflexive else f(other_data, self_data) TypeError: ufunc 'right_shift' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe'' ```