code: def dropna(self, dim, how='any', thresh=None):
          
          ds = self._to_temp_dataset().dropna(dim, how=how, thresh=thresh)
          return self._from_temp_dataset(ds)
docs: Returns a new array with dropped labels for missing values along
          the provided dimension.
  
          Parameters
          ----------
          dim : str
              Dimension along which to drop missing values. Dropping along
              multiple dimensions simultaneously is not yet supported.
          how : {'any', 'all'}, optional
              * any : if any NA values are present, drop that label
              * all : if all values are NA, drop that label
          thresh : int, default None
              If supplied, require this many non-NA values.
  
          Returns
          -------
          DataArray