p: ['S', 'I', 'R']
 t: ['S->I', 'I->R']
pre: [[1 1 0]
 [0 1 0]]
post: [[0 2 0]
 [0 0 1]]
h: <function sir.<locals>.<lambda> at 0x7330e9db63e0>
m: [197   3   0]
