"targets": [
        {
          "datasource": {
            "type": "prometheus",
            "uid": "${DS_PROMETHEUS}"
          },
          "exemplar": true,
          "expr": "sum by (server) (minio_node_replication_average_active_workers{job=\"$scrape_jobs\"})",
          "interval": "1m",
          "intervalFactor": 2,
          "legendFormat": "{{server}}",
          "refId": "A"

func TestExp2(t *testing.T) {
	testExp2(t, Exp2, "Exp2")
	testExp2(t, Exp2Go, "Exp2Go")
}

func testExp2(t *testing.T, Exp2 func(float64) float64, name string) {
	for i := 0; i < len(vf); i++ {
		if f := Exp2(vf[i]); !close(exp2[i], f) {
			t.Errorf("%s(%g) = %g, want %g", name, vf[i], f, exp2[i])
		}
	}
	for i := 0; i < len(vfexp2SC); i++ {
		if f := Exp2(vfexp2SC[i]); !alike(exp2SC[i], f) {

      "targets": [
        {
          "datasource": {
            "type": "prometheus",
            "uid": "${DS_PROMETHEUS}"
          },
          "exemplar": true,
          "expr": "sum by (server) (minio_cluster_replication_received_bytes{job=\"$scrape_jobs\"})",
          "interval": "1m",
          "intervalFactor": 2,
          "legendFormat": "{{server}}",
          "refId": "A"
        }

			}
		case "var":
			expr = &ast.StarExpr{Star: (*r.Expr).Pos(), X: expr}
		case "macro":
			expr = &ast.CallExpr{Fun: expr}
		}
	case ctxSelector:
		if r.Name.Kind == "var" {
			expr = &ast.StarExpr{Star: (*r.Expr).Pos(), X: expr}
		} else {
			error_(r.Pos(), "only C variables allowed in selector expression %s", fixGo(r.Name.Go))
		}
	case ctxType:

		tmpl, err := New("empty").Parse(text)
		if err != nil {
			t.Fatalf("%q: %s", test.expr, err)
		}
		b.Reset()
		err = tmpl.Execute(b, &cmpStruct)
		if test.ok && err != nil {
			t.Errorf("%s errored incorrectly: %s", test.expr, err)
			continue
		}
		if !test.ok && err == nil {
			t.Errorf("%s did not error", test.expr)
			continue
		}

		info := Info{
			Types: make(map[ast.Expr]TypeAndValue),
		}
		name := mustTypecheck(test.src, nil, &info).Name()

		// look for expression
		var expr ast.Expr
		for e := range info.Types {
			if ExprString(e) == test.expr {
				expr = e
				break
			}
		}
		if expr == nil {
			t.Errorf("package %s: no expression found for %s", name, test.expr)
			continue
		}
		tv := info.Types[expr]

		info := Info{
			Types: make(map[syntax.Expr]TypeAndValue),
		}
		name := mustTypecheck(test.src, nil, &info).Name()

		// look for expression
		var expr syntax.Expr
		for e := range info.Types {
			if ExprString(e) == test.expr {
				expr = e
				break
			}
		}
		if expr == nil {
			t.Errorf("package %s: no expression found for %s", name, test.expr)
			continue
		}
		tv := info.Types[expr]

		st.advance(2)
		typ := st.demangleType(false)
		expr := st.expression()
		offset := 0
		if len(st.str) > 0 && (st.str[0] == 'n' || isDigit(st.str[0])) {
			offset = st.number()
		}
		if len(st.str) == 0 || st.str[0] != 'E' {
			st.fail("expected E after pointer-to-member conversion")
		}
		st.advance(1)
		return &PtrMemCast{
			Type:   typ,
			Expr:   expr,
			Offset: offset,
		}

	// In both the open source world (via Code Search) and the
	// Google source tree, (?P<expr>name) and (?<expr>name) are the
	// dominant forms of named captures and both are supported.
	startsWithP := len(t) > 4 && t[2] == 'P' && t[3] == '<'
	startsWithName := len(t) > 3 && t[2] == '<'

	if startsWithP || startsWithName {
		// position of expr start
		exprStartPos := 4
		if startsWithName {
			exprStartPos = 3
		}

//
// - By using the type CompileAssert<(bool(expr))>, we ensures that
//   expr is a compile-time constant.  (Template arguments must be
//   determined at compile-time.)
//
// - The outer parentheses in CompileAssert<(bool(expr))> are necessary
//   to work around a bug in gcc 3.4.4 and 4.0.1.  If we had written
//
//     CompileAssert<bool(expr)>
//
//   instead, these compilers will refuse to compile
//