Dataframe related operations in pandas: intercept one or several rows, splice, and add a row

import pandas as pd

data = pd.DataFrame()
series = pd.Series({
    
    "x":1,"y":2},name="a")
data = data.append(series)
print(data)
data = data.append(series)
print(data)

     x    y
a  1.0  2.0
     x    y
a  1.0  2.0
a  1.0  2.0