class_docstr: The DaskInterface allows a Dataset objects to wrap a dask
  DataFrame object. Using dask allows loading data lazily
  and performing out-of-core operations on the data, making
  it possible to work on datasets larger than memory.
  
  The DaskInterface covers almost the complete API exposed
  by the PandasInterface with two notable exceptions:
  
  1) Sorting is not supported and any attempt at sorting will
     be ignored with an warning.
  2) Dask does not easily support adding a new column to an existing
     dataframe unless it is a scalar, add_dimension will therefore
     error when supplied a non-scalar value.
  4) Not all functions can be easily applied to a dask dataframe so
     some functions applied with aggregate and reduce will not work.
docstr: Dask does not support iloc, therefore iloc will execute
  the call graph and lose the laziness of the operation.
docstr_tok: ["Dask","does","not","support","iloc",",","therefore","iloc","will","execute","the","call","graph","and","lose","the","laziness","of","the","operation","."]
code: def iloc(cls, dataset, index):
      """
      Dask does not support iloc, therefore iloc will execute
      the call graph and lose the laziness of the operation.
      """
      rows, cols = index
      scalar = False
      if isinstance(cols, slice):
          cols = [d.name for d in dataset.dimensions()][cols]
      elif np.isscalar(cols):
          scalar = np.isscalar(rows)
          cols = [dataset.get_dimension(cols).name]
      else:
          cols = [dataset.get_dimension(d).name for d in index[1]]
      if np.isscalar(rows):
          rows = [rows]
  
      data = {}
      for c in cols:
          data[c] = dataset.data[c].compute().iloc[rows].values
      if scalar:
          return data[cols[0]][0]
      return tuple(data.values())
  
imports: import sys
  import numpy
  import pandas
  from ..None import util
  from ..dimension import Dimension
  from ..element import Element
  from ..ndmapping import NdMapping, item_check, sorted_context
  from .interface import Interface
  from .pandas import PandasInterface
label_desc: Use image node_id 20 for calling the DaskInterface obj's underlying member method code with example usage: obj.iloc(cls, dataset, index) and returns: tuple, data