"TypeError: index 0 has type 'QgsRasterLayer' but 'QgsRasterCalculatorEntry' is expected." error when calculating NDVI Landsat 5 with PyQGIS

I start to write my own simple code to automatically calculate NDVI from Landsat 5.

Here is my code:

from PyQt5.QtGui import *from qgis.analysis import *land_3 = 'D:\park\LT05_L1TP_131047_19871207_20170418_01_T1_B3.tif'land_4 = 'D:\park\LT05_L1TP_131047_19871207_20170418_01_T1_B4.tif'rasterb3 = iface.addRasterLayer(land_3, "B3")rasterb4 = iface.addRasterLayer(land_4, "B4")ir = QgsRasterCalculatorEntry()r = QgsRasterCalculatorEntry()ir = rasterb4r = rasterb3arr = (ir, r, ir, r)exp = "1.0*(%s-%s)/(1.0*(%s+%s)"%arroutput = 'D:\\park\\output.tif'e = rasterb3.extent()w = rasterb3.width()h = rasterb3.height()entries = [ir,r]ndvi = QgsRasterCalculatorEntry()ndvi = QgsRasterCalculator(exp, output, "GTiff", e, w, h, entries)ndvi.processCalculation()lyr = iface.addRasterLayer(output,"NDVI")

But this error shown up:

Traceback (most recent call last):  File "D:\QGIS\apps\Python37\lib\code.py", line 90, in runcode    exec(code, self.locals)  File "<input>", line 1, in <module>  File "<string>", line 25, in <module>TypeError: index 0 has type 'QgsRasterLayer' but 'QgsRasterCalculatorEntry' is expected.