# Returns the maximum value
	#
	# https://docs.mongodb.com/manual/reference/operator/aggregation/max/
	#
	# ~~~json
	# { $max: <expression> }
	# ~~~
	#
	# `$max` compares both value and type, using the specified BSON comparison
	# order for values of different types.
	fun max(field: String, expression: Serializable): MongoGroup do
		return acc("max", field, expression)
	end