func (p *UserAgent) iMessagePreview() bool {
	if !strings.Contains(p.ua, "facebookexternalhit") {
		return false
	}
	if !strings.Contains(p.ua, "Twitterbot") {
		return false
	}
	p.bot = true
	p.browser.Name = "iMessage-Preview"
	p.browser.Engine = ""
	p.browser.EngineVersion = ""
	return true
}
Returns true if we think that it is iMessage-Preview. This function also
modifies some attributes in the receiver accordingly.
package user_agent
import (
	"regexp"
	"strings"
)
var botFromSiteRegexp = regexp.MustCompile(`http[s]?: 
func getFromSite(comment []string) string {
	if len(comment) == 0 {
		return ""
	}
	idx := 2
	if len(comment) < 3 {
		idx = 0
	} else if len(comment) == 4 {
		idx = 3
	}
	results := botFromSiteRegexp.FindStringSubmatch(comment[idx])
	if len(results) == 1 {
		if idx == 0 {
			return results[0]
		}
		return strings.TrimSpace(comment[idx-1])
	}
	return ""
}
func (p *UserAgent) googleOrBingBot() bool {
	if strings.Contains(p.ua, "Google") || strings.Contains(p.ua, "bingbot") {
		p.platform = ""
		p.undecided = true
	}
	return p.undecided
}