# Two Choice

A state can define multiple transitions, each attached to a different event. Whichever
event occurs first determines the next state, allowing the state machine to branch —
the basis of decision tasks.

In this example, `WaitForChoice` waits for activity on either port 1 or port 2
(`Port1_High` or `Port2_High`). The LED of the chosen port is then lit at maximum
intensity for one second before the state machine exits.

![image](state_machines/examples/two_choice__light.svg)![image](state_machines/examples/two_choice__dark.svg)

### Python

```python
from bpod_core.fsm import StateMachine

fsm = StateMachine()

fsm.add_state(
    name='WaitForChoice',
    transitions={'Port1_High': 'LightPort1', 'Port2_High': 'LightPort2'},
)
fsm.add_state(
    name='LightPort1',
    timer=1,
    transitions={'Tup': '>exit'},
    actions={'PWM1': 255},
)
fsm.add_state(
    name='LightPort2',
    timer=1,
    transitions={'Tup': '>exit'},
    actions={'PWM2': 255},
)
```

### JSON

```json
{
  "states": {
    "WaitForChoice": {
      "transitions": {
        "Port1_High": "LightPort1",
        "Port2_High": "LightPort2"
      }
    },
    "LightPort1": {
      "timer": 1.0,
      "transitions": {
        "Tup": ">exit"
      },
      "actions": {
        "PWM1": 255
      }
    },
    "LightPort2": {
      "timer": 1.0,
      "transitions": {
        "Tup": ">exit"
      },
      "actions": {
        "PWM2": 255
      }
    }
  }
}
```

### YAML

```yaml
states:
  WaitForChoice:
    transitions:
      Port1_High: LightPort1
      Port2_High: LightPort2
  LightPort1:
    timer: 1.0
    transitions:
      Tup: '>exit'
    actions:
      PWM1: 255
  LightPort2:
    timer: 1.0
    transitions:
      Tup: '>exit'
    actions:
      PWM2: 255
```