def slice!(slice = nil)
      raise(Exception, "Slicing unavailable!") unless sliced?
      if slice.present?
        if slice.to_i.in?(1..slice_number)
          @current_slice = slice.to_i
        else
          raise(ArgumentError, "Slice number must be Integer in (1..#{slice_number}). #{slice.inspect} passed.")
        end
      end
      self
    end
def slice!(slice = nil)
      raise(Exception, "Slicing unavailable!") unless sliced?
      if slice.present?
        if slice.to_i.in?(1..slice_number)
          @current_slice = slice.to_i
        else
          raise(ArgumentError, "Slice number must be Integer in (1..#{slice_number}). #{slice.inspect} passed.")
        end
      end
      self
    end
General slicing method. Passing the argument changes the +current_slice+.