Remove Duplicates from array in python

remove_duplicate.py

# remove duplicate from array in place
# below function returns modified array
# time complexity of this program is O(nlogn) + O(n) that is nothing but O(nlogn).
def remove_duplicate(arr):
    arr.sort()         # sort array that will take O(nlogn) time
    l = len(arr)
    if l == 0 or l == 1: # check for a base condition
        return arr
      
    x = 0 # extra pointer
    
    for i in range(0, l-1):
        if arr[i] != arr[i+1]:
            arr[x] = arr[i] # shifting element to front of array
            x += 1
    arr[x] = arr[l-1]
    x += 1
    return arr[:x]

arr = [10,20,10,10,20,30,40] # original array
print(remove_duplicate(arr))
# the output will be [10,20,30,40]
# but if you try to print(arr) the output will be [10,20,30,40,20,30,40]