input: Write a python function to fetch data from a given URL based on a provided zipcode using the requests library.
  assert fetch_data('12345') == {'expected_key': 'expected_value'}
  assert fetch_data('67890') == {'another_key': 'another_value'}
  assert fetch_data('00000') == 'Error: 404'
output: def fetch_data(zipcode):
      import requests
      
      url = f"https://example.com/data/{zipcode}"
      
      try:
          response = requests.get(url)
          response.raise_for_status()
          return response.json()
      except requests.exceptions.HTTPError as http_err:
          if response.status_code == 404:
              return 'Error: 404'
          else:
              return f'Error: {response.status_code}'
      except Exception as err:
          return f'Error: {err}'