Screen Link: https://app.dataquest.io/m/315/functions%3A-fundamentals/11/combining-functions

My Code: opened_file = open(‘AppleStore.csv’)

from csv import reader

read_file = reader(opened_file)

apps_data = list(read_file)

def extract(data_set, index):

column =

for row in data_set[1:]:

value = row[index]

column.append(value)

return column

def find_sum(a_list):

a_sum = 0

for element in a_list:

a_sum += float(element)

return a_sum

def find_length(a_list):

length = 0

for element in a_list:

length += 1

return length

def mean(data_set, index):

column = extract(data_set, index)

return find_sum(column) / find_length(column)

avg_price = mean(apps_data, 4)

I do not understand why we need to use: column = extract(data_set, index) and can not just use return find_sum(a_list) / find_length(a_list) ?

I am asking myself what is ‘a_list’ doing in the sum and length functions before, when I do not define it and also do not use it?

Thank you all!