Oh, interesting usage of this Python stuff. Thanks for the explanation.

Here, [-1,1] is the array and this [g=="boy"] indicates the position of the array to be taken based on the condition. If the gender = "boy", then [-1, 1][1] would return 1 as the condition is true and if the gender = "girl", then [-1, 1][0] would return -1 as the condition is false. Basically, it is a [array][position] arrangement.

Like for this one, but what is [-1,1][g=="boy"]? How it is work and when you can use this?

Both work.

if gender == "boy": 
    return boy_height 
elif gender == "girl":  
    return girl_height

You must write == insted of 'is'.