input: Write a python function to demonstrate the use of try, except, and finally blocks by attempting to read a file that may not exist.
  assert read_file("existing_file.txt") == "File content"
  assert read_file("non_existing_file.txt") == "An error occurred"
  assert read_file("another_existing_file.txt") == "Another file content"
output: def read_file(file_path):
      try:
          with open(file_path, 'r') as file:
              content = file.read()
              return content
      except FileNotFoundError:
          return "An error occurred"
      finally:
          print(f"Attempted to read file: {file_path}")