PyQt Izgarası AÇılmıyor Yardım(PYTHON)

KODLAR BUNLAR ARKADAŞLAR PYQT IZGARASI AÇILMIYOR NEDENİNİ ALYAMADIM

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# -*- coding: cp1254 -*-
from PyQt4.QtGui import *
from PyQt4.QtCore import *

class YakitHesaplayicisi(QDialog):
def __init__(self, ebeveyn=None):
super(yakitHesaplayicisi, self).__init__(ebeveyn)
grid=QGridLoyaut()
grid.addWidget(QLabel('Gideceginiz yol (KM):'),0,)
self.gidilenYol=QLineEdit()
self.gidilenYol.setInputMask('0000000000')

grid.addWidget(self.gidilenYol,0,1)

grid.addWidget(QLabel('Yakıtın Litre Fiyati'),1,0)
self.yakitFiyati=QLineEdit()
self.yakitFiyati.setInputMask('0.00')
grid.addWidget(self.tutar,2,1)

grid.addWidget(QLabel('Toplam Tutar: '),3,0)
self.tutar=QLabel('<i>KM giriniz</i>')
grid.addWidget(self.tutar,3,1)

hesaplaDugme=QPushButton('Hesapla')
self.connect(hesaplaDugme,4,0,1,2)

self.setLayout(grid)
self.setWindowsTitle('Yakit Hesaplayicisi')

def yakitHesapla(self):
yol=0
try: yol=int(self.gidilenYol.text())
except: pass
fiyat=0
try: fiyat=float(self.yakitFiyati.text())
except: pass
tuketim=0
try: tuketim=float(self.yakitTuketimi.text())
except: pass

if not yol:
self.tutar.setText('<font color="red"><i>KM giriniz</i></font>')
self.gidilenYol.setFocus()

elif not fiyat:
self.tutar.setText('font color="red"><i>Fiyat Giriniz</i><font>')
self.yakitFiyati.setFocus()

elif not tuketim:
self.tutar.setText('<font color="red"><i>Tüketim Giriniz</i><font>')
self.yakitTuketimi.setFocus()

else:
tutar=fiyat*(yol*tuketim)/100
self.tutar.setText('<font color="blue"><b>%0.2f</b> TL</font>' % tutar)

uyg=QApplication([])
pencere=YakitHesaplayicisi()
pencere.show()
uyg.exec_()
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