func TestCheckUnaryExprAddString(t *testing.T) {
	env := MakeSimpleEnv()
	expectCheckError(t, `+ "abc"`, env,
		`invalid operation: + untyped string`,
	)
}
Test + String
package eval
import (
	"testing"
)
func TestCheckUnaryExprAddInt(t *testing.T) {
	env := MakeSimpleEnv()
	expectConst(t, `+ 4`, env, NewConstInt64(+ 4), ConstInt)
}
func TestCheckUnaryExprAddRune(t *testing.T) {
	env := MakeSimpleEnv()
	expectConst(t, `+ '@'`, env, NewConstRune(+ '@'), ConstRune)
}
func TestCheckUnaryExprAddFloat(t *testing.T) {
	env := MakeSimpleEnv()
	expectConst(t, `+ 2.0`, env, NewConstFloat64(+ 2.0), ConstFloat)
}
func TestCheckUnaryExprAddComplex(t *testing.T) {
	env := MakeSimpleEnv()
	expectConst(t, `+ 8.0i`, env, NewConstComplex128(+ 8.0i), ConstComplex)
}
func TestCheckUnaryExprAddBool(t *testing.T) {
	env := MakeSimpleEnv()
	expectCheckError(t, `+ true`, env,
		`invalid operation: + untyped bool`,
	)
}