func (rows *Rows) Del(i int) (row *Row) {
	if i < 0 {
		return
	}
	if i >= rows.Len() {
		return
	}
	row = (*rows)[i]
	last := len(*rows) - 1
	copy((*rows)[i:], (*rows)[i+1:])
	(*rows)[last] = nil
	(*rows) = (*rows)[0:last]
	return row
}
Del will detach row at index `i` from slice and return it.
package tabula
import (
	"fmt"
	"math/rand"
	"time"
)
type Rows []*Row
func (rows *Rows) Len() int {
	return len(*rows)
}
func (rows *Rows) PushBack(r *Row) {
	if r != nil {
		(*rows) = append((*rows), r)
	}
}
func (rows *Rows) PopFront() (row *Row) {
	l := len(*rows)
	if l > 0 {
		row = (*rows)[0]
		(*rows) = (*rows)[1:]
	}
	return
}
func (rows *Rows) PopFrontAsRows() (newRows Rows) {
	row := rows.PopFront()
	if nil == row {
		return
	}
	newRows.PushBack(row)
	return
}