function Measure-TimeSpan([TimeSpan]$Span, $Units=$Null)
{
   switch ($Units)
   {
   "Weeks"        {[Int]($Span.TotalDays / 7)}
   "Days"         {[Int]$Span.TotalDays}
   "Hours"        {[Int]$Span.TotalHours}
   "Minutes"      {[Int]$Span.TotalMinutes}
   "Seconds"	  {[Int]$Span.TotalSeconds}
   "MilliSeconds" {[Int64]$Span.TotalMilliSeconds}
   "Ticks"        {$Span.Ticks}
   default        {$null}
   }
}


function Measure-Since([DateTime]$Time, $Units=$Null)
{
   $Since = Measure-TimeSpan $([DateTime]::Now - $Time) $Units
   if ($Since -eq $null)
   {
      throw 'Usage: Measure-Since -Time <DateTime> -Units ["Weeks","Days","Hours","Minutes","Seconds","Milliseconds","Ticks"]'
   }
   else
   {
      $Since
   }
}


function Measure-Till([DateTime]$Time, $Units=$Null)
{
   $Since = Measure-TimeSpan $($Time - [DateTime]::Now) $Units
   if ($Since -eq $null)
   {
      throw 'Usage: Measure-Till -Time <DateTime> -Units ["Weeks","Days","Hours","Minutes","Seconds","Milliseconds","Ticks"]'
   }
   else
   {
      $Since
   }
}

Set-Alias MSince Measure-Since
Set-Alias MTill  Measure-Till