old_contents: import pytest
  from binascii import unhexlify, hexlify
  from pypeerassets.transactions import *
  
  
new_contents: import pytest
  from decimal import Decimal, getcontext
  getcontext().prec = 6
  from pypeerassets.transactions import *
  
  
  @pytest.mark.parametrize("tx_size", [181, 311])
  def test_calculate_transaction_fee(tx_size):
  
      assert round(calculate_tx_fee(tx_size), 2) == round(Decimal(0.01), 2)
  
subject: implement calculate_transaction_fee test