adding envs tagging/interpolation

exec_extra/funcs_cmdargopt.go

@@ -0,0 +1,13 @@
+package exec_extra
+
+import (
+	`r00t2.io/goutils/bitmask`
+)
+
+// BitMask returns the underlying bitmask.MaskBit representation of a cmdArgOpt.
+func (c cmdArgOpt) BitMask() (b bitmask.MaskBit) {
+
+	b = bitmask.MaskBit(c)
+
+	return
+}