from collections import OrderedDict
from binascii import hexlify, unhexlify
from calendar import timegm
from datetime import datetime
import json
import struct
import time

from .account import PublicKey
from .chains import known_chains
from .signedtransactions import Signed_Transaction
from .operations import Operation
from .objects import GrapheneObject, isArgsThisClass

timeformat = '%Y-%m-%dT%H:%M:%S%Z'


def getBlockParams(ws):
    """ Auxiliary method to obtain ``ref_block_num`` and
        ``ref_block_prefix``. Requires a websocket connection to a
        witness node!
    """
    dynBCParams = ws.get_dynamic_global_properties()
    ref_block_num = dynBCParams["head_block_number"] & 0xFFFF
    ref_block_prefix = struct.unpack_from("<I", unhexlify(dynBCParams["head_block_id"]), 4)[0]
    return ref_block_num, ref_block_prefix


def formatTimeFromNow(secs=0):
    """ Properly Format Time that is `x` seconds in the future

     :param int secs: Seconds to go in the future (`x>0`) or the past (`x<0`)
     :return: Properly formated time for Graphene (`%Y-%m-%dT%H:%M:%S`)
     :rtype: str

    """
    return datetime.utcfromtimestamp(time.time() + int(secs)).strftime(timeformat)

from collections import OrderedDict
from binascii import hexlify, unhexlify
from calendar import timegm
from datetime import datetime
import json
import struct
import time

from .account import PublicKey
from .chains import known_chains
from .signedtransactions import Signed_Transaction
from .operations import Operation
from .objects import GrapheneObject, isArgsThisClass

timeformat = '%Y-%m-%dT%H:%M:%S%Z'


def getBlockParams(ws):
    """ Auxiliary method to obtain ``ref_block_num`` and
        ``ref_block_prefix``. Requires a websocket connection to a
        witness node!
    """
    dynBCParams = ws.get_dynamic_global_properties()
    ref_block_num = dynBCParams["last_irreversible_block_num"] & 0xFFFF
    ref_block_prefix = struct.unpack_from("<I", unhexlify(dynBCParams["head_block_id"]), 4)[0]
    return ref_block_num, ref_block_prefix


def formatTimeFromNow(secs=0):
    """ Properly Format Time that is `x` seconds in the future

     :param int secs: Seconds to go in the future (`x>0`) or the past (`x<0`)
     :return: Properly formated time for Graphene (`%Y-%m-%dT%H:%M:%S`)
     :rtype: str

    """
    return datetime.utcfromtimestamp(time.time() + int(secs)).strftime(timeformat)

--- 
+++ 
@@ -21,7 +21,7 @@
         witness node!
     """
     dynBCParams = ws.get_dynamic_global_properties()
-    ref_block_num = dynBCParams["last_irreversible_block_num"] & 0xFFFF
+    ref_block_num = dynBCParams["head_block_number"] & 0xFFFF
     ref_block_prefix = struct.unpack_from("<I", unhexlify(dynBCParams["head_block_id"]), 4)[0]
     return ref_block_num, ref_block_prefix
 
Revert "[TaPOS] link to the last irreversible block instead of headblock"

This reverts commit 05cec8e450a09fd0d3fa2b40860760f7bff0c125.
