input: Write a function to extract phone numbers starting with '08' from a list of phone numbers. Return the extracted phone numbers as a list. If the input list is empty, return an empty list.
  assert extract_phone_numbers(['0834567', '0945678', '07123456', '08901234', '07890123'])==['0834567', '08901234']
  assert extract_phone_numbers(['0945678', '07123456', '07890123'])==[]
  assert extract_phone_numbers([])==[]
output: def extract_phone_numbers(phone_numbers):
      return [number for number in phone_numbers if number.startswith('08')]