input: Write a function to filter out duplicate strings from a list of strings.
  assert filter_list(["abc", "def", "abc", "ghi", "jkl", "mno", "abc", "pqr"]) == ["abc", "def", "ghi", "jkl", "mno", "pqr"]
  assert filter_list(["apple", "banana", "apple", "cherry", "banana", "date"]) == ["apple", "banana", "cherry", "date"]
  assert filter_list(["one", "two", "three", "one", "four", "two"]) == ["one", "two", "three", "four"]
output: def filter_list(strings):
      seen = set()
      filtered = []
      for string in strings:
          if string not in seen:
              seen.add(string)
              filtered.append(string)
      return filtered