Address PR comments

registry.go

@@ -177,14 +177,14 @@ func (r *PrefixedRegistry) Each(fn func(string, interface{})) {
 		}
 	}
 
-	baseRegistry, prefix := walkRegistries(r, "")
+	baseRegistry, prefix := findPrefix(r, "")
 	baseRegistry.Each(wrappedFn(prefix))
 }
 
-func walkRegistries(registry Registry, prefix string) (Registry, string) {
+func findPrefix(registry Registry, prefix string) (Registry, string) {
 	switch r := registry.(type) {
 	case *PrefixedRegistry:
-		return walkRegistries(r.underlying, r.prefix + prefix)
+		return findPrefix(r.underlying, r.prefix + prefix)
 	case *StandardRegistry:
 		return r, prefix
 	}

registry_test.go

@@ -2,7 +2,6 @@ package metrics
 
 import (
 	"testing"
-	"github.com/stretchr/testify/assert"
 )
 
 func BenchmarkRegistry(b *testing.B) {
@@ -281,7 +280,10 @@ func TestWalkRegistries(t *testing.T) {
 	c := NewCounter()
 	Register("bars", c)
 
-	_, prefix := walkRegistries(r2, "")
-	assert.Equal(t, "prefix.prefix2.", prefix)
+	_, prefix := findPrefix(r2, "")
+	if "prefix.prefix2." !=  prefix {
+		t.Fatal(prefix)
+	}
+
 
 }