sum
min
max
avg
group
stddev
stdvar
count
count_values
bottomk
topk
quantile
on
ignoring
group_right
group_left
by
without
offset

----------------------------------------------------

[
	["keyword", "sum"],
	["keyword", "min"],
	["keyword", "max"],
	["keyword", "avg"],
	["keyword", "group"],
	["keyword", "stddev"],
	["keyword", "stdvar"],
	["keyword", "count"],
	["keyword", "count_values"],
	["keyword", "bottomk"],
	["keyword", "topk"],
	["keyword", "quantile"],
	["keyword", "on"],
	["keyword", "ignoring"],
	["keyword", "group_right"],
	["keyword", "group_left"],
	["keyword", "by"],
	["keyword", "without"],
	["keyword", "offset"]
]
