String "interning" attempt

[Serge]

Hi Nim community, is the following code safe or does it create a memory leak 
(i.e. will the values stored in the table be garbage collected or not)?
    
    
    import tables
    
    var strTable = initTable[string,  ptr string]()
    
    proc internSting(s: string): ptr string =
        if s in strTable:
            return strTable[s]
        else:
            strTable[s] = unsafeAddr(s)
            return strTable[s]
    
    
    var a = "hello"
    var b = "hello"
    
    a = internSting(a)[]
    b = internSting(b)[]
    
    echo "a = ", a
    echo "b = ", b
    
    echo (a == b)
    echo (addr(a) == addr(b))
    
    
    Run