def merge_region(position_region, delta=1):
    """Merge a batch of sorted region

    Parameters
    ----------
    ``position_region``: a list like, required
        A regions (2D) array, format like: [[start1,end1], [start2,end2], ...]

    ``delta``: Integer, optinal

    Example
    -------
    ...
    >>> from basevar import utils
    >>> utils.merge_region([[1,1], [2,3], [4,6], [4,5], [8, 20], [9, 12]])
    ... [[1, 6], [8, 20]]

    """

    # sorted
    position_region.sort(key=lambda x:x[0])

    m_region = []
    prepos, start, end = '', '', ''
    flag = False
    for s, e in position_region:
        if s > e:
            print >> sys.stderr,('[ERROR]Your region start > end.'
                                 ' It is not allow when call Merge function\n')
            sys.exit(1)

        if prepos == '':
            # # The light is on => Get the region!
            if flag: m_region.append([start, end])
            start, end = s, e
            flag = True

        else:
            if prepos > s:
                print >> sys.stderr,('[ERROR]The array hasn\'t been sorted.\n')
                sys.exit(1)

            if delta + end >= s:
                end = e if e > end else end

            else:
                m_region.append([start, end])
                start, end = s, e

        prepos = s

    if flag: m_region.append([start, end])
    return m_region