if you do run thisyou'll notice that pycalc implements normal calculator model-expressions are evaluated as enterednot all at once at the end that isparts of an expression are computed and displayed as soon as operator precedence and manually typed parentheses allow the result in figure - for instancereflects pressing " "and then repeatedly pressing "*to display successive powers of 'll explain how this evaluation works in moment pycalc' calcgui class builds the gui interface as frames of buttons much like the simple calculator of the previous sectionbut pycalc adds host of new features among them are another row of action buttonsinherited methods from guimixin (presented in ) new "cmdbutton that pops up nonmodal dialogs for entry of arbitrary python codeand recent calculations history pop up figure - captures some of pycalc' pop-up windows you may enter expressions in pycalc by clicking buttons in the guityping full expressions in command-line pop upsor typing keys on your keyboard pycalc intercepts key press events and interprets them the same as corresponding button pressestyping is like pressing the buttonthe space bar key is "clear,enter is "eval,backspace erases characterand is like pressing "help the command-line pop-up windows are nonmodal (you can pop up as many as you likethey accept any python code--press the run button or your enter key to evaluate text in their input fields the result of evaluating this code in the calculator' namespace text and language