code: def add_dimension(cls, dataset, dimension, dim_pos, values, vdim):
      import xarray as xr
  
      if not vdim:
          raise Exception(
              "Cannot add key dimension to a dense representation."
          )
      dim = dimension_name(dimension)
      coords = {
          d.name: cls.coords(dataset, d.name) for d in dataset.kdims
      }
      arr = xr.DataArray(
          values,
          coords=coords,
          name=dim,
          dims=tuple(d.name for d in dataset.kdims[::-1]),
      )
      return dataset.data.assign(**{dim: arr})
  
imports: import sys
  import types
  import numpy
  import pandas
  from ..None import util
  from ..dimension import Dimension, asdim, dimension_name
  from ..element import Element
  from ..ndmapping import NdMapping, item_check, sorted_context
  from .grid import GridInterface
  from .interface import DataError, Interface
  from .util import dask_array_module, finite_range
label_desc: Use image node_id 27 for calling the XArrayInterface obj's underlying member method code with example usage: obj.add_dimension(cls, dataset, dimension, dim_pos, values, vdim) and returns: dataset