code: def aggregate(cls, dataset, dimensions, function, **kwargs):
      reindexed = dataset.reindex(dimensions)
      grouped = (
          cls.groupby(reindexed, dimensions, list, "raw")
          if len(dimensions)
          else [((), reindexed.data)]
      )
  
      rows = []
      for k, group in grouped:
          if isinstance(function, np.ufunc):
              reduced = function.reduce(group, axis=0, **kwargs)
          else:
              reduced = function(group, axis=0, **kwargs)
          rows.append(
              np.concatenate(
                  [k, (reduced,) if np.isscalar(reduced) else reduced]
              )
          )
      return np.atleast_2d(rows), []
  
imports: import numpy
  from ..None import util
  from ..dimension import dimension_name
  from ..element import Element
  from ..ndmapping import NdMapping, item_check, sorted_context
  from .interface import DataError, Interface
label_desc: Use image node_id 17 for calling the ArrayInterface obj's underlying member method code with example usage: obj.aggregate(cls, dataset, dimensions, function) and returns: np,  list