input: Write a python function to filter strings from a list based on a given filter function.
  assert filter_strings(['apple', 'banana', 'cherry', 'date'], lambda x: 'a' in x) == ['apple', 'banana', 'date']
  assert filter_strings(['apple', 'banana', 'cherry', 'date'], lambda x: len(x) > 5) == ['banana', 'cherry']
  assert filter_strings(['apple', 'banana', 'cherry', 'date'], lambda x: x.startswith('d')) == ['date']
output: def filter_strings(strings, filter_func):
      return [s for s in strings if filter_func(s)]