How to output a nested list or 2D array while using loops.in Python

Question

test2 = []
test3 = []
for k in range(62):
    for j in range(34):
        PS = bin_power(df_eeg.iloc[k*1024:(k+1)*1024, j], [0.5,4,7,12,30], 1024)[0][2]
        test3.ap