mc_rebalance_datapack/data/minecraft/villager/professions/librarian.json

{
	"levels": {
		"1": {
			"take": {
				"type": "constant",
				"value": 5
			},
			"trades": [
				{
					"sells": {"item": "emerald","count": 1},
					"wants": [{"item": "enchanted_book","count":1}]
				},
				{
					"sells": {"item": "book","functions":[{"function":"enchant_randomly"}],"count": 1},
					"wants": [{"item": "emerald","count":10}]
				},
				{
					"sells": {"item": "book","functions":[{"function":"enchant_randomly"}],"count": 1},
					"wants": [{"item": "emerald","count":10}]
				}, 
				{
					"sells": {"item": "book","functions":[{"function":"enchant_randomly"}],"count": 1},
					"wants": [{"item": "emerald","count":10}]
				},
				{
					"sells": {"item": "book","functions":[{"function":"enchant_randomly"}],"count": 1},
					"wants": [{"item": "emerald","count":10}]
				}

			]
		}
	}
}