I have modified mist to test my new functions. Right now, mist check if the input file contains a petri net or doesn't and informs the user.

I have also create a python script that uses this 'new mist' and compare the results given with the results of the function is_petri_net from the other script.

Right now, the 'new mist' concludes that examples/PN+ZEROTEST/rw.spec is not a petri net but the old is_petri_net functions cloncludes that it's a correct petri net. It seems that the old function is right.

I'll check what's happening here.

There are also some comments with helpfull prints on typchecking.c that will be removed after check that it works right