--task 1
	select 
	    user_id,
	    indexOf(tags, 'promo') as promo_index,
	    arrayJoin(tags)
	from events
	where has(tags, 'promo')
	
	-- task 2
	select
	    user_id,
	    scores['math']      as math_score,
	    mapValues(scores)   as all_values
	from metrics
	
	-- task 3
	select 
	    name,
	    contact.type as contact_type,
	    contact.value as contact_value
	from users_nested
	array join contacts as contact
	where contact.type = 'email'