Python Function Code Challenge

I have been able to get past part 1 of this code challenge where I create the function add_list() which returns the summation of all of the numbers in the list.

I am stuck though on the part 2 where it wants you to return a string of the list and then the summation of the list which is found when using the add_list() function. The error keeps telling me that it is "expecting str" but is finding an int. I may not be using the .join() function correctly so the compiler keeps finding integers rather than strings. Any feedback would be great, thanks.

def add_list(list): new_item= 0 for i in list: new_item += i return new_item

def summarize(list): string_list= ' , '.join(list) list_form= list.split() return("The sum of ["+ string_list + "] is "+add_list(list_form))