>>> from artropode import Artropode, tagmes_iguals

>>> f = Artropode('Formica rufa', 'Formiga roja', 3)
>>> e = Artropode('Leptinotarsa decemlineata', 'Escarabat de la patata', 3)
>>> p = Artropode('Palinurus elephas', 'Llagosta vermella', 2)
>>> tagmes_iguals([f, e])
3
>>> tagmes_iguals([f, e, p])
-1

>>> tagmes_iguals([f, e, f, f, f, e, e, e])
3
>>> tagmes_iguals([f, e, e, e, f, e, p, f, f, e])
-1