input: Write a python function to extract phone numbers from a given text.
  assert extract_phone_numbers("This is a sample text. Mr. Smith's cell phone number is (123) 456-7890 and Mrs. Smith's phone number is (321) 234-5678.") == ['(123) 456-7890', '(321) 234-5678']
  assert extract_phone_numbers("Contact us at 123-456-7890 or 987-654-3210.") == ['123-456-7890', '987-654-3210']
  assert extract_phone_numbers("No phone numbers here!") == []
output: import re
  
  def extract_phone_numbers(text):
      pattern = r'\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}'
      return re.findall(pattern, text)