def guess(span, mode = :middle)
      return span if not mode
      return span.begin + span.width / 2 if span.width > 1 and (mode == true or mode == :middle)
      return span.end if mode == :end
      span.begin
    end
def guess(span, mode = :middle)
      return span if not mode
      return span.begin + span.width / 2 if span.width > 1 and (mode == true or mode == :middle)
      return span.end if mode == :end
      span.begin
    end
Guess a specific time within the given span.

 span - The Chronic::Span object to calcuate a guess from.

 Returns a new Time object.