+### DO NOT INDENT LINES CONTAINING $(call xyz) AS THIS MAY CHANGE THE CONTEXT
+### OF THE FIRST LINE IN THE CALLED VARIABLE (NOTE: variable!)
+### see http://www.gnu.org/software/make/manual/html_node/Call-Function.html#Call-Function
+### ACTUALLY IT IS A SIMPLE MACRO EXPANSION
+
+### use round brackets for make variables, and curly brackets for shell variables
+