# Pass the argument `value` as the parameter `key`.
	#
	# Return `self`.
	#
	# ```
	# var query = (new CypherQuery).
	# 		nmatch("(n)").
	# 		nwhere("n.key = \{key\}").
	#		set("key", "foo")
	#
	# assert query.params["key"] == "foo"
	# ```
	#
	# SEE: `[]=`
	fun set(key: String, value: nullable Serializable): SELF do
		self[key] = value
		return self
	end