ESOUI - How do I identify whether a character is in a particular Guild like Fighters or Mages

Here's my code.

Lua Code:

-- /dump d(ZGV.Utils.SkillLines(false,true,false,true,true))
function Utils.SkillLines(showType,showLineInfo,showLineXP,showSkillAbilities,showAbilityInfo)
    if showType then
        d("Number of Skill Types: "..GetNumSkillTypes().."\n-----------------------------")
    end
    if showLineInfo then
        for index = 0,GetNumSkillLines(SKILL_TYPE_GUILD) do
            d(index..": "..GetSkillLineInfo(SKILL_TYPE_GUILD, index))
        end
        d("-----------------------------")
    end
    if showLineXP then
        for index = 0,GetSkillLineXPInfo(SKILL_TYPE_GUILD) do
            d(index..": "..GetSkillLineXPInfo(SKILL_TYPE_GUILD, index))
        end
        d("-----------------------------")
    end
    if showSkillAbilities then
        for index = 0,GetNumSkillAbilities(SKILL_TYPE_GUILD) do
            d(index..": "..GetNumSkillAbilities(SKILL_TYPE_GUILD, index))
        end
        d("-----------------------------")
    end
    if showAbilityInfo then
        local hasProgression, progressionIndex, lastRankXP, nextRankXP, currentXP, atMorph = GetAbilityProgressionXPInfoFromAbilityId(abilityId)
        local skillType, skillIndex, abilityIndex = GetSkillAbilityIndicesFromProgressionIndex(progressionIndex)
        local abilityId2 = GetSkillAbilityId(skillType, skillIndex, abilityIndex)
        d("GetSkillAbilityId: "..abilityId2)
        d("skillType: "..skillType)
        d("skillIndex: "..skillIndex)
        d("abilityIndex: "..abilityIndex)
        d("-----------------------------")
        if hasProgression then d("hasProgression: true") else d("hasProgression: false") end
        d("progressionIndex: "..progressionIndex)
        d("lastRankXP: "..lastRankXP)
        d("nextRankXP: "..nextRankXP)
        d("currentXP: "..currentXP)
        if atMorph then d("atMorph: true") else d("atMorph: false") end
        d("-----------------------------")
    end
end

And what it outputs

It's based off of this text file. As far as I know, these appear to be the only public functions that provide skill line information. However, it does so in a generalized way and not in the way I need.

Basically what I am looking for is a simple boolean against a Guild to see if it appears in the list of Skills (e.g. false returned if player isn't in the Fighters guild, or true returned if player is in the Mages guild, etc.).

Any ideas?