Adjusts an xs:date value to a specific timezone, or to no timezone at all;
            the result is the date in the target timezone that contains the starting instant of the
            supplied date.
fn:adjust-date-to-timezone( $arg as xs:date?xs:date?fn:adjust-date-to-timezone( $arg as xs:date?,$timezone as xs:dayTimeDuration?xs:date? If $timezone is not specified, then the effective value of
               $timezone is the value of the implicit timezone in the dynamic
            context.
 If $arg is the empty sequence, then the function returns the empty
            sequence.
 If $arg does not have a timezone component and $timezone is
            the empty sequence, then the result is the value of $arg.
 If $arg does not have a timezone component and $timezone is
            not the empty sequence, then the result is $arg with $timezone
            as the timezone component.
 If $arg has a timezone component and $timezone is the empty
            sequence, then the result is the local value of $arg without its timezone
            component.
 If $arg has a timezone component and $timezone is not the
            empty sequence, then the function returns the value of the expression:
Let $dt be the value of fn:dateTime($arg,
                     xs:time('00:00:00')).
Let $adt be the value of fn:adjust-dateTime-to-timezone($dt,
                     $timezone)
					
The function returns the value of xs:date($adt)
					
Assume the dynamic context provides an implicit timezone of -05:00
                  (-PT5H0M).
let $tz-10 := xs:dayTimeDuration("-PT10H")
The expression fn:adjust-date-to-timezone(xs:date("2002-03-07")) returns xs:date("2002-03-07-05:00").
The expression fn:adjust-date-to-timezone(xs:date("2002-03-07-07:00")) returns xs:date("2002-03-07-05:00").
The expression fn:adjust-date-to-timezone(xs:date("2002-03-07"),
                  $tz-10) returns xs:date("2002-03-07-10:00").
The expression fn:adjust-date-to-timezone(xs:date("2002-03-07-07:00"),
                  $tz-10) returns xs:date("2002-03-06-10:00").
The expression fn:adjust-date-to-timezone(xs:date("2002-03-07"),
                  ()) returns xs:date("2002-03-07").
The expression fn:adjust-date-to-timezone(xs:date("2002-03-07-07:00"),
                  ()) returns xs:date("2002-03-07").
A dynamic error is raised  if $timezone
            is less than -PT14H or greater than PT14H or is not an
            integral number of minutes.