Consider the following code $($which can be copy$/$pasted into google colab$)$:

data$=$np$.$array $([0,1,4,9,16,25])$ #Here is some sample data

difference$=$np$.$zeros$($len$($data$)-1)$ #'difference' is a new array filled with zeroes.

print$(\text{'}$difference before the "for" loop:$\text{'},$ difference$)$

print$(\text{'}ln\text{'}$