Three things [the disciples] stated before R' Yishmael, and he would not state either a prohibition or a permit regarding them; and R' Yehoshua ben Masya clarified them: [They asked about] one who squeezes a boil on the Sabbath. [R' Yehoshua ben Masya clarified:] If [his intent is] to make an opening for it, he is liable, but if [his intent is] to remove the pus from it, he is not liable.  And [they asked the law] regarding one who traps a snake on the Sabbath. [R' Yehoshua ben Masya clarified:] If he is involved with it so that it will not bite him, he is not liable. But if [he traps it] for medicinal use, he is liable.  And [they asked the law] regarding sealed pots. [R' Yehoshua ben Masya clarified] that in the tent of a corpse they are tahor, but they are tamei when carried by a zav. R' Elazar ben Tzadok says: They are also tahor when carried by a zav, because their processing has not been completed.