input: Write a function to clean and format phone numbers using regular expressions.
  assert clean_phone_number('(800) 555-1234') == '(800) 555-1234'
  assert clean_phone_number('032-536-9222') == '(032) 536-9222'
  assert clean_phone_number('541.766.4455') == '(541) 766-4455'
  assert clean_phone_number('123-456-7890') == '(123) 456-7890'
  assert clean_phone_number('123-45-6789') == None
output: import re
  
  def clean_phone_number(phone):
      pattern = re.compile(r'^\(?(\d{3})\)?[-.\s]?(\d{3})[-.\s]?(\d{4})$')
      match = pattern.match(phone)
      if match:
          return f'({match.group(1)}) {match.group(2)}-{match.group(3)}'
      return None