Instructions Add a command to this chapter’s case study program that allows the user to view the contents of a file in the current working directory. When the command is selected, the program should display a list of filenames and a prompt for the name of the file to be viewed. Be sure to include error recovery in the program. If the user enters a filename that does not exist they should be prompted to enter a filename that does exist. An example of the program input and output is shown below: /root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 7 Files in /root/sandbox: filesys.py example.txt Enter a file name from these names: example.txt THIS IS CONTENT OF AN EXAMPLE FILE. /root/sandbox 1 List the current directory 2 Move up 3 Move down 4 Number of files in the directory 5 Size of the directory in bytes 6 Search for a file name 7 View the contents of a file 8 Quit the program Enter a number: 8 Have a nice day!   """ File: filesys.py Project 6.6 Provides a menu-driven tool for navigating a file system and gathering information on files. Adds a command to view a file's contents. """ import os, os.path QUIT = '8' COMMANDS = ('1', '2', '3', '4', '5', '6', '8') MENU = """1   List the current directory 2   Move up 3   Move down 4   Number of files in the directory 5   Size of the directory in bytes 6   Search for a file name 8   Quit the program""" def main():     while True:         print(os.getcwd())         print(MENU)         command = acceptCommand()         runCommand(command)         if command == QUIT:             print("Have a nice day!")             break def acceptCommand():     """Inputs and returns a legitimate command number."""     while True:         command = input("Enter a number: ")         if not command in COMMANDS:             print("Error: command not recognized")         else:             return command def runCommand(command):     """Selects and runs a command."""     if command == '1':         listCurrentDir(os.getcwd())     elif command == '2':         moveUp()     elif command == '3':         moveDown(os.getcwd())     elif command == '4':         print("The total number of files is", \               countFiles(os.getcwd()))     elif command == '5':         print("The total number of bytes is", \               countBytes(os.getcwd()))     elif command == '6':         target = input("Enter the search string: ")         fileList = findFiles(target, os.getcwd())         if not fileList:             print("String not found")         else:             for f in fileList:                 print(f)      # add your condition here     elif command == '8':            print("Files in", os.getcwd())            print(listCurrentDir(os.getcwd()))     viewFile = input("Enter a file name from these names: ")     viewFile() def viewFile(dirName):    # write your code here    f = open("viewFile", "r")    print(f.read)     print("") def listCurrentDir(dirName):     """Prints a list of the cwd's contents."""     lyst = os.listdir(dirName)     for element in lyst: print(element) def moveUp():     """Moves up to the parent directory."""     os.chdir("..") def moveDown(currentDir):     """Moves down to the named subdirectory if it exists."""     newDir = input("Enter the directory name: ")     if os.path.exists(currentDir + os.sep + newDir) and \        os.path.isdir(newDir):         os.chdir(newDir)     else:         print("ERROR: no such name") def countFiles(path):     """Returns the number of files in the cwd and     all its subdirectories."""     count = 0     lyst = os.listdir(path)     for element in lyst:         if os.path.isfile(element):             count += 1         else:             os.chdir(element)             count += countFiles(os.getcwd())             os.chdir("..")     return count def countBytes(path):     """Returns the number of bytes in the cwd and     all its subdirectories."""     count = 0     lyst = os.listdir(path)     for element in lyst:         if os.path.isfile(element):             count += os.path.getsize(element)         else:             os.chdir(element)             count += countBytes(os.getcwd())             os.chdir("..")     return count def findFiles(target, path):     """Returns a list of the file names that contain     the target string in the cwd and all its subdirectories."""     files = []     lyst = os.listdir(path)     for element in lyst:         if os.path.isfile(element):             if target in element:                 files.append(path + os.sep + element)         else:             os.chdir(element)             files.extend(findFiles(target, os.getcwd()))             os.chdir("..")     return files if __name__ == "__main__":     main()