code: def from_chars(chars):
          
          paulis = [pauli_from_char(c, n) for n, c in enumerate(chars) if c != "I"]
          if not paulis:
              return 1.0 * I
          if len(paulis) == 1:
              return 1.0 * paulis[0]
          return reduce(lambda a, b: a * b, paulis)
docs: Make Pauli's Term from chars which is written by "X", "Y", "Z" or "I".
          e.g. "XZIY" => X(0) * Z(1) * Y(3)
  
          Args:
              chars (str): Written in "X", "Y", "Z" or "I".
  
          Returns:
              Term: A `Term` object.
  
          Raises:
              ValueError: When chars conteins the character which is "X", "Y", "Z" nor "I".