






"""simple docstring"""



def 						_SCREAMING_SNAKE_CASE (    __snake_case			:  int    ):





  '''simple docstring'''





  assert (
      isinstance(SCREAMING_SNAKE_CASE_		,					SCREAMING_SNAKE_CASE_    ) and number_of_steps > 0
  ), f'number_of_steps needs to be positive integer, your input {number_of_steps}'
  if number_of_steps == 1:
    return 1
  lowercase							    =       1, 1
  for _ in range(number_of_steps - 1    ):
    lowercase							    =       current + previous, current
  return current


if __name__ == "__main__":
    import doctest

    doctest.testmod()





def 	snake_case__			(    SCREAMING_SNAKE_CASE_		:    str			):



     '''simple docstring'''





     if not all(x.isalpha() for x in string			):
          raise ValueError('String must only contain alphabetic characters.'			)

     lowercase__    :   Optional[int]      =       sorted(string.lower()			)
     return len(SCREAMING_SNAKE_CASE_			) == len(set(SCREAMING_SNAKE_CASE_			)			)


if __name__ == "__main__":
       snake_case_			  = input('''Enter a string ''').strip()

       snake_case_			  = is_isogram(input_str)
       print(F'''{input_str} is {'an' if isogram else 'not an'} isogram.''')

