iso8601_timediv

# File lib/date/format.rb, line 1289
  def iso8601_timediv(n) # :nodoc:
    strftime('T%T' +
             if n < 1
               ''
             else
               '.%0*d' % [n, (sec_fraction / Rational(1, 10**n)).round]
             end +
             '%:z')
  end