How to read and write tif files using GDAL in python

import gdal
def readTif(fileName):
 dataset = (fileName)
 if dataset == None:
  print(fileName+"File cannot be opened")
  return
 im_width =  #Number of columns in raster matrix im_height =  #Number of rows of raster matrix im_bands =  #Number of bands im_data = (0,0,im_width,im_height)#Get data im_geotrans = ()#Get affine matrix information im_proj = ()#Get projection information im_blueBand = im_data[0,0:im_height,0:im_width]#Get blue band im_greenBand = im_data[1,0:im_height,0:im_width]#Get green band im_redBand = im_data[2,0:im_height,0:im_width]#Get the red band im_nirBand = im_data[3,0:im_height,0:im_width]#Obtain the near-infrared band

#Save tif file functionimport gdal
import numpy as np
def writeTiff(im_data,im_width,im_height,im_bands,im_geotrans,im_proj,path):
 if 'int8' in im_data.:
  datatype = gdal.GDT_Byte
 elif 'int16' in im_data.:
  datatype = gdal.GDT_UInt16
 else:
  datatype = gdal.GDT_Float32

 if len(im_data.shape) == 3:
  im_bands, im_height, im_width = im_data.shape
 elif len(im_data.shape) == 2:
  im_data = ([im_data])
 else:
  im_bands, (im_height, im_width) = 1,im_data.shape
  #Create a file driver = ("GTiff")
 dataset = (path, im_width, im_height, im_bands, datatype)
 if(dataset!= None):
  (im_geotrans) #Write affine transformation parameters  (im_proj) #Write projection for i in range(im_bands):
  (i+1).WriteArray(im_data[i])
 del dataset