docs: def integrate(self, coord, 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
              Can be 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: Dataset
  
          See also
          --------
          DataArray.integrate
          numpy.trapz: corresponding numpy function
          """
          if not isinstance(coord, (list, tuple)):
              coord = (coord, )
          result = self
          for c in coord:
              result = result._integrate_one(c, datetime_unit=datetime_unit)
          return result