input: Write a python function to filter strings containing the letter 'b' from a list.
  assert filter_strings_with_b(['foo', 'bar', 'baz', 'hello', 'world']) == ['bar', 'baz']
  assert filter_strings_with_b(['banana', 'apple', 'berry', 'cherry']) == ['banana', 'berry']
  assert filter_strings_with_b(['grape', 'pear', 'peach']) == []
output: def filter_strings_with_b(strings):
      return [s for s in strings if 'b' in s]