Variables: 
bool[1]: "x" 
bool[2]: "y" 
chan[1]: "X" 

Event graph: 
event[0]: fork: null, #pred: 0, succ: 1 

# process[0]:
event[1]: fork: , pid: 0, #pred: 1, succ: 3 4 2 
event[2]: send: [after=20] X!(true), pid: 0, #pred: 1, succ: 2 
channel deps: 1 
event[3]: receive: X?(x), pid: 0, #pred: 1, succ: 3 
channel deps: 1 
event[4]: receive: X?(y), pid: 0, #pred: 1, succ: 4 
channel deps: 1 

