In what situations can knowing the index of an item in a list be useful?
Why might a programmer want to define his or her own functions? What are some potential disadvantages? How might new functions make debugging more complicated?
What are some situations in which you would use the len function to find the length of a list?
What is an example of a situation in which you might use the append method? In what ways is the append method limited?
What is the difference between a method and a function? In what ways are they similar? Why do you think Python makes a distinction between methods and functions?

We have to define our functions as well, and that is known as the user-defined functions. And to be precise we should not worry at all, as there is no potential disadvantage of the functions we define on our own. The only disadvantage can be that it might not be in a standard format. However, we have design patterns now, and each programmer knows the required format hence. However, for a layman, this can be a problem. And that is the only potential disadvantage related to the user-defined function.

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