Return a ti for the most recent period of the
  desired frequency.
latestWeek(xTi = today())
latestMonth(xTi = today())
latestQuarter(xTi = today())
latestHalf(xTi = today())
latestYear(xTi = today())
latestQ4(xTi = today())
latestJanuary(xTi = today())
latestFebruary(xTi = today())
latestMarch(xTi = today())
latestApril(xTi = today())
latestMay(xTi = today())
latestJune(xTi = today())
latestJuly(xTi = today())
latestAugust(xTi = today())
latestSeptember(xTi = today())
latestOctober(xTi = today())
latestNovember(xTi = today())
latestDecember(xTi = today())a ti object or something that the ti()
  function can turn into a ti object
All return return ti objects as described in the details.
The latest{whatever} functions are the same as the
  corresponding current{whatever} functions, except that they
  return the most recent completed ti of the desired frequency.
  A period is considered to be completed on it last day.  For example,
  if today is Thursday, then latestWedweek() returns the week
  that ended yesterday.  Yesterday it would have returned the same week,
  but the day before that (Tuesday) it would have returned the
  "wwednesday" ti for the week that had ended six days before.
latestWeek returns the weekly ti for the most recently
  completed week as of xTi.  If the xTi is itself a
  ti, the returned week is the most recently completed week as of
  the last day of xTi.  (Note that the default weekly frequency
  is "wmonday" (Monday-ending weeks), so latestWeek always
  returns "wmonday" ti's.)  See
  setDefaultFrequencies to change this.
All of the other latest{SomeFreq} functions work the same way,
  returning the ti's for the most recently completed SomeFreq as
  of the last day of xTi. The tif's (frequencies) for
  latestHalf and latestQ4 are "semiannual" and
  "quarterly", respectively.
latestJanuary returns the monthly ti for January of the
  most recently completed January-ending year that the last day of its
  argument falls into.  latestFebruary returns the monthly
  ti for February of the most recently completed February-ending
  year that the last day of its argument falls into, and so on.