How to get a set of values from a list so that the order of the set is such that the order in the list is still preserved in the set?

Question

The list in my actual code is too large.
Is there a way to get the desired output.
An efficient way will be preferred.
Here is my code:

import sys
def function():
    listt=["the","cat","sat","on","the","mat","which","is","on","the","floor"]
    print (sorted(set(listt)))
function()

Output:['cat', 'floor', 'is', 'mat', 'on', 'sat', 'the', 'which']
Expected Output:["the","cat","sat","on","mat","which","is","floor"]