# This program takes a list and removes all of
# t he duplicate elements

def removeDuplicates(L):
    unique = []
    for x in L:
        if x not in unique:
            unique.append(x)
    L[0:] = []  # deletes everything in L
    for x in unique:
        L.append(x)
    
def main():
    L = [1, 4, 2, 3, 1, 5, 4, 3, 2, 1]
    removeDuplicates(L)
    print( L )

main()