Add simple filter example

examples/threefold/tfgrid3deployer/filter.vsh

@@ -0,0 +1,20 @@
+#!/usr/bin/env -S v -gc none  -cc tcc -d use_openssl -enable-globals -cg run
+
+import freeflowuniverse.herolib.threefold.grid3.deployer
+
+const gigabyte = u64(1024 * 1024 * 1024)
+
+// We can use any of the parameters for the corresponding Grid Proxy query
+// https://gridproxy.grid.tf/swagger/index.html#/GridProxy/get_nodes
+
+filter := deployer.FilterNodesArgs{
+	size:      5
+	randomize: true
+	free_mru:  8 * gigabyte
+	free_sru:  50 * gigabyte
+	farm_name: 'FreeFarm'
+	status:    'up'
+}
+
+nodes := deployer.filter_nodes(filter)!
+println(nodes)