Nim implementation of Ruby tap() method

[janAkali]

That's very easy to fix, use a `block` to avoid clash of identifiers:
    
    
    template tapIt*[T](obj: T, code: untyped): T =
      block:
        let it {.inject.} = obj
        code
        it
    
    var num = 123
    echo num.tapIt(echo 2 * it)
    echo num.tapIt(echo 3 * it)
    
    
    Run