public static String getHash(String email) {
        if (TextUtils.isEmpty(email)) {
            return null;
        }
        email = email.trim().toLowerCase(US);
        return email.length() > 0 ? digest(email) : null;
    }
Get avatar hash for specified e-mail address

@param email
@return hash
app/src/main/java/com/github/pockethub/android/util/GravatarUtils.java