如下图所示，学校食堂要将大米的入库和出库数据，合并到文件“合并.csv”中。其中入库数据文件为"入库.csv"，出库数据文件为"出库.csv"，文件"入库.csv"、文件"出库.csv"和“合并.csv”都放置在程序所在的文件夹，请补全代码。
import csv
in1=[]
in2=[]
with open('/data/入库.csv') as f1:
rows = list( ① )
for a in rows:
in1. ②
with open('/data/出库.csv') as f2:
rows = list( csv.reader (f2))
for a in rows:
in2. ③
with open('合并.csv', 'w', encoding='utf_8_sig', newline='') as f3:
writer = csv.writer(f3)
for a in in1:
writer.writerow(a)
for a in in2:
writer. ④
