how to remove a duplicated latter in a string python code example

Example 1: Python program to remove duplicate characters of a given string.

>>> foo = 'mppmt'
>>> ''.join(sorted(set(foo), key=foo.index))
'mpt'

Example 2: python remove duplicates words from string

def unique_list(l):
    ulist = []
    [ulist.append(x) for x in l if x not in ulist]
    return ulist

a="calvin klein design dress calvin klein"
a=' '.join(unique_list(a.split()))