def slice( start, length )
      values = @values.collect do |value|
        value.dimension == 0 ? value : value.slice( start, length )
      end
      self.class.new( *values ).demand
    end
def slice( start, length )
      values = @values.collect do |value|
        value.dimension == 0 ? value : value.slice( start, length )
      end
      self.class.new( *values ).demand
    end
Extract array view with part of array

 @param [Integer,Node] start Number of elements to skip.
 @param [Integer,Node] length Size of array view.

 @return [Node] Array view with the specified elements.

 @private