parameters: (self, key, ndim, subset=None)
docstring: sub-classes to define
          return a sliced object
  
          Parameters
          ----------
          key : string / list of selections
          ndim : 1,2
              requested ndim of result
          subset : object, default None
              subset to act on
docstring_summary: sub-classes to define
          return a sliced object
docstring_tokens: sub - classes to define return a sliced object
function: def _gotitem(self, key, ndim, subset=None):
          """
          sub-classes to define
          return a sliced object
  
          Parameters
          ----------
          key : string / list of selections
          ndim : 1,2
              requested ndim of result
          subset : object, default None
              subset to act on
  
          """
          raise AbstractMethodError(self)
function_tokens: def _gotitem ( self , key , ndim , subset = None ) : raise AbstractMethodError ( self )