Adding env.HasEnv for single-value env exist logic

envs/funcs.go

@@ -118,3 +118,17 @@ func GetPidEnvMapNative(pid uint32) (envMap map[string]interface{}, err error) {
 
 	return
 }
+
+/*
+	HasEnv is much like os.LookupEnv, but only returns a boolean for
+	if the environment variable key exists or not.
+
+	This is useful anywhere you may need to set a boolean in a func call
+	depending on the *presence* of an env var or not.
+*/
+func HasEnv(key string) (envIsSet bool) {
+
+	_, envIsSet = os.LookupEnv(key)
+
+	return
+}