Use a for-in loop to iterate through a map

  - 
  
 assignStep 
 : 
  
 assign 
 : 
  
 - 
  
 map 
 : 
  
 1 
 : 
  
 10 
  
 2 
 : 
  
 20 
  
 3 
 : 
  
 30 
  
 - 
  
 sum 
 : 
  
 0 
 - 
  
 loopStep 
 : 
  
 for 
 : 
  
 value 
 : 
  
 key 
  
 # key = 1, 2, 3 
  
 in 
 : 
  
 ${keys(map)} 
  
 # [1, 2, 3] 
  
 steps 
 : 
  
 - 
  
 sumStep 
 : 
  
 assign 
 : 
  
 - 
  
 sum 
 : 
  
 ${sum + map[key]} 
 - 
  
 returnStep 
 : 
  
 return 
 : 
  
 ${sum} 
  
 # sum is 60