code: def solution(self):
          
          num = self.num
  
          solution_file = os.path.join(EULER_DATA, 'solutions.txt')
          solution_line = linecache.getline(solution_file, num)
  
          try:
              answer = solution_line.split('. ')[1].strip()
          except IndexError:
              answer = None
  
          if answer:
              return answer
          else:
              msg = 'Answer for problem %i not found in solutions.txt.' % num
              click.secho(msg, fg='red')
              click.echo('If you have an answer, consider submitting a pull '
                         'request to EulerPy on GitHub.')
              sys.exit(1)
docs: Returns the answer to a given problem