def before(date)
      date = Time.parse date if date.is_a? String
      commits = CommitCollection.new
      each do |commit|
        commits << commit if commit.committed_date < date
      end
      commits
    end
def before(date)
      date = Time.parse date if date.is_a? String
      commits = CommitCollection.new
      each do |commit|
        commits << commit if commit.committed_date < date
      end
      commits
    end
Returns the commits in this collection that have been committed before
 the given time

 @param [Time, Date, DateTime, String] date The time to use as the upper
        limit to filter the commits
 @return [CommitCollection] The commits that have been committed after the
         given date
 @see Commit#committed_date
 @see Time.parse