[Python] quick sort python recursion

This is my quick sort code, the partition function works well, but I got a problem while calling the recursion. The pos changes every time it starts the function and then the list limits are change as well. How to fix that?

def partition(lst, start, end):

pos=0
if len(lst)<2:
return
for i in range(len(lst[start:end])):
if lst < lst[end]:
lst,lst[pos]=lst[pos],lst
pos+=1

elif i==(len(lst[start:end])-1):
lst[end],lst[pos]=lst[pos],lst[end]

return pos

def quick_sort_recursive(lst, start, end):

pos=partition(lst, start, end)
if start<=pos<=end :
quick_sort_recursive(lst, start, pos-1)
quick_sort_recursive(lst, pos+1, end)
else:
return lst

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