define parent
	echo "parent has two parameters: $1, $2"
	$(call child,$1)
endef

define child
	echo "child has one parameter: $1"
 	ifndef $2
		echo "but child can also see parent's second parameter: $2!"
	else
		echo "and child cannot see parent's second parameter !"
	endif
endef

scoping_issue:
	@$(call parent,one, two)