func (ins *Log) String() string {
	return fmt.Sprintf("%s = log(%s)", ins.Result, ins.X)
}
String is the human-readable description of the instruction.
package vm
import (
	"fmt"
	"github.com/elliotchance/ok/ast/asttest"
	"github.com/elliotchance/ok/number"
)
type Log struct {
	X, Result Register
}
func (ins *Log) Execute(_ *int, vm *VM) error {
	vm.Set(ins.Result, asttest.NewLiteralNumber(
		number.Log(
			number.NewNumber(vm.Get(ins.X).Value),
		).String(),
	))
	return nil
}