Hi Zabbix Team, 
we would like to use Usermacros in calculated item while using foreach_functions:

for example:
current working:
count(exists_foreach(/*/device.status?[tag="device_type:Router" and tag="country:US"]))

we want to use the Usermacro {$COUNTRY} like:
{$COUNTRY} = "US"
count(exists_foreach(/*/device.status?[tag="device_type:Router" and tag="country:\{$COUNTRY}"]))

if this is to complicated it would also be nice to build something like:
{$COUNTRY} = "country:US"
count(exists_foreach(/*/device.status?[tag="device_type:Router" and tag="\{$COUNTRY}"]))