input: Write a function to clean up a list of emails by removing any text after the '+' character and before the '.uk' extension, if present. Return the cleaned list of emails. If the original list is empty, return an empty list.
  assert clean_emails(['bob@example.com', 'alice+bob@cafe.com', 'bob@gmail.com.uk', 'bob+alice@example'])==['bob@example.com', 'alice@cafe.com', 'bob@gmail.com', 'bob@example']
  assert clean_emails(['alice@cafe.com', 'bob@gmail.com', 'carol@example.uk'])==['alice@cafe.com', 'bob@gmail.com', 'carol@example']
  assert clean_emails([])==[]
output: def clean_emails(emails):
      cleaned_emails = []
      for email in emails:
          if '+' in email:
              email = email.split('+')[0]
          if '.uk' in email:
              email = email.split('.uk')[0] + '.uk'
          cleaned_emails.append(email)
      return cleaned_emails