func IsIMDbID(str string) bool {
	_, err := FormatIMDbID(str)
	return err == nil
}
IsIMDbID returns true if the string is in a valid IMDbID format.
package movies
import (
	"errors"
	"fmt"
	"regexp"
	"strconv"
	"strings"
)
const BaseURL = "https://www.imdb.com"
func FormatIMDbID(id string) (string, error) {
	id = strings.TrimLeft(id, "t")
	idNum, err := strconv.Atoi(id)
	if idNum < 0 {
		return "", errors.New("negative number in IMDB ID")
	}
	if err != nil {
		return "", err
	}
	return fmt.Sprintf("tt%07d", idNum), nil
}