def remove_duplicates(lst):
lstreturn = []
for value in lst:
if value not in lstreturn:
lstreturn.append(value)
return lstreturn
lst = ["python", "java", "python", "c", "c", "php", "c"]
lst = remove_duplicates(lst)
print(lst)
'''
run:
['python', 'java', 'c', 'php']
'''