Write a GUI-based program that simulates a simple pocket calculator. The GUI displays a single entry field for output. The GUI should also display a keypad of buttons for the 10 digits and 6 command...

Write a GUI-based program that simulates a simple pocket calculator. The GUI displays a single entry field for output. The GUI should also display a keypad of buttons for the 10 digits and 6 command buttons labeled +, -, *, /, C, and =. The command C should clear the output field. The command = calculates an answer and displays it in the field. The program should build a string from the user’s button clicks and echo it in the field. The program should detect any errors during this process and display the word “ERR” in the field.