How do you delete extra \n's from a file?

Question

I am new to coding and am trying to make a function that will add the numbers given in a file. I have a solution that gives me the sum of the numbers but there is a "None" value being returned as well. How do I stop this from happening? My code looks like this

def addIntegersFromFile(file):

    newfile = file
    total = 0
    with open(newfile, 'r') as numbers:
        number = numbers.read()
        list1 = number.strip("\n")
        list2 = list1.split("\n")
    for value in list2:
        total += float(value)
    print(total)

It will return the sum of a file and then a new line with a "None" value.

Ex:

6.0
None