def unpack_bitstr(rev_cur_bit, bitstr):
 bstr_len = len(bitstr)
 return ''.join([rev_cur_bit[bitstr[i:(i + 2)]] for i in range(0, bstr_len, 2)])

def unpack_bitstr ( rev_cur_bit , bitstr ) : bstr_len = len ( bitstr ) return '' . join ( [ rev_cur_bit [ bitstr [ i : ( i + 2 ) ] ] for i in range ( 0 , bstr_len , 2 ) ] )
unpack bistring into nt sequence .