func ungroup() {
	regexp.MustCompile(`(?:x)+`)
	regexp.MustCompile(`(?:[abc])+`)
}
(?:x) -> x
package checker_test
import (
	"regexp"
)
func multiPass() {
	regexp.MustCompile(`[a-a]`)
	regexp.MustCompile(`(?:a|b|c)`)
}
func altCommonPrefixSuffix() {
	regexp.MustCompile(`foo|fo`)
	regexp.MustCompile(`(?:http|https): 
	regexp.MustCompile(`xpath|path`)
	regexp.MustCompile(`❤path|path`)
	regexp.MustCompile(`fo|fo❤`)
}
func merge() {
	regexp.MustCompile(`x[abcd][abcd]*y`)
	regexp.MustCompile(`axx*y`)
}