divide gprs pfo to several clusters

calculator/calculator.go

@@ -1,5 +1,10 @@
 // Package calculator does simple calculations.
 package calculator // Add takes two numbers and returns the result of adding them together.
+
 func Add(a, b float64) float64 {
-        return a + b
+	return a + b
+}
+
+func Subtract(a, b float64) float64 {
+	return b - a
 }

calculator/calculator_test.go

@@ -1,16 +1,24 @@
 package calculator_test
 
 import (
-        "calculator"
-        "testing"
+	"calculator"
+	"testing"
 )
 
 func TestAdd(t *testing.T) {
-        t.Parallel()
-        var want float64 = 4
-        got := calculator.Add(2, 2)
-        if want != got {
-                t.Errorf("want %f, got %f", want, got)
-        }
+	t.Parallel()
+	var want float64 = 4
+	got := calculator.Add(2, 2)
+	if want != got {
+		t.Errorf("want %f, got %f", want, got)
+	}
 }
 
+func TestSubtract(t *testing.T) {
+	t.Parallel()
+	var want float64 = 2
+	got := calculator.Subtract(4, 2)
+	if want != got {
+		t.Errorf("want %f, got %f", want, got)
+	}
+}