t.swift

extension RangeReplaceableCollectionType  {
    
    
    public func slice(start: Int, _ stop: Int = 0, _ step: Int = 1) -> [Generator.Element] {
        
        var _stop = stop
        if stop == 0 {
            _stop = self.count as! Int
        }
        var sliced = Array<Generator.Element>()
        
        for (idx, val) in self.enumerate() {
            
            if idx % step != 0 {
                continue
            }
            if idx < start {
                continue
            }
            if idx > _stop {
                continue
            }
            sliced.append(val)
        }
        
        return sliced
        
    }
    
}