finally did assert_function_call

for cleaner reading, like all other instruction asserts

test/slot_machine/instructions/test_simple_call.rb

@@ -24,8 +24,7 @@ module SlotMachine
       assert_slot_to_reg 4 ,:message , 1 , :message
     end
     def test_5_call
-      assert_equal Risc::FunctionCall , risc(5).class
-      assert_equal :meth , risc(5).method.name
+      assert_function_call 5 , :meth
     end
     def test_6_label
       assert_label 6 , "after_meth_"

test/slot_machine/macro/test_init.rb

@@ -31,8 +31,7 @@ module SlotMachine
         assert_reg_to_slot 10 , "id_space_" , :message , 2
         assert_load 11 , Risc::Label , "id_label_"
         assert_reg_to_slot 12 , "id_label_" , :message , 4
-        assert_equal Risc::FunctionCall, risc(13).class
-        assert_equal :main, risc(13).method.name
+        assert_function_call 13 , :main
         assert_label 14 , "Object.__init__"
         assert_transfer 15 , :message , :saved_message
         assert_slot_to_reg 16 ,:message , 5 , :message