What am I missing here? (async)

[xioren]

Quick question. Making testType a ref object fixed the issue but does it still 
need to be a var? The code still works when I use let which is slightly 
confusing to me.

e.g.:
    
    
    import asyncdispatch
    
    
    type testType = ref object
      testField: bool
    
    
    proc testProc(thing: testType) {.async.} =
      if thing.testField:
        thing.testField = false
    
    
    proc newThing(): testType =
      new result
      result.testField = true
    
    
    let x = newThing()
    waitFor testProc(x)
    echo x.testField
    
    
    Run

I admittedly have very little experience with ref types.