docs: def integrate(self, dim, datetime_unit=None):
          """ integrate the array with the trapezoidal rule.
  
          .. note::
              This feature is limited to simple cartesian geometry, i.e. coord
              must be one dimensional.
  
          Parameters
          ----------
          dim: str, or a sequence of str
              Coordinate(s) used for the integration.
          datetime_unit: str, optional
              Can be used to specify the unit if datetime coordinate is used.
              One of {'Y', 'M', 'W', 'D', 'h', 'm', 's', 'ms', 'us', 'ns',
                      'ps', 'fs', 'as'}
  
          Returns
          -------
          integrated: DataArray
  
          See also
          --------
          numpy.trapz: corresponding numpy function
  
          Examples
          --------
  
          >>> da = xr.DataArray(np.arange(12).reshape(4, 3), dims=['x', 'y'],
          ...                   coords={'x': [0, 0.1, 1.1, 1.2]})
          >>> da
          <xarray.DataArray (x: 4, y: 3)>
          array([[ 0,  1,  2],
                 [ 3,  4,  5],
                 [ 6,  7,  8],
                 [ 9, 10, 11]])
          Coordinates:
            * x        (x) float64 0.0 0.1 1.1 1.2
          Dimensions without coordinates: y
          >>>
          >>> da.integrate('x')
          <xarray.DataArray (y: 3)>
          array([5.4, 6.6, 7.8])
          Dimensions without coordinates: y
          """
          ds = self._to_temp_dataset().integrate(dim, datetime_unit)
          return self._from_temp_dataset(ds)