             throw GraphError.VertexNotPresent
         }
 
-        var result: [Vertex] = []
+        var result = [Vertex]()
 
         for row in 0..<size {
             if matrix[row, index] == 1 {

            throw GraphError.VertexNotPresent
        }

        var result: [Vertex] = []

        for row in 0..<index {
            if matrix[row, index] == 1 {

        if col >= nCols {
            return Bit.Zero
        }
        var newContents = [T]()
        for (index, item) in contents.enumerate() {
            if (index % nCols) != 0 {
                newContents.append(item)
