input: Write a function that retrieves strings of a certain length from a given list of strings.
  assert get_strings_of_length(['Python', 'list', 'exercises', 'practice', 'solution'], 8) == ['practice', 'solution']
  assert get_strings_of_length(['Python', 'list', 'exercises', 'practice', 'solution'], 6) == ['Python']
  assert get_strings_of_length(['Python', 'list', 'exercises', 'practice', 'solution'], 9) == ['exercises']
output: def get_strings_of_length(strings_list, length):
      return [s for s in strings_list if len(s) == length]