dictionary is thrown up in the main window for use in larger expressions you can use this as an escape mechanism to employ external tools in your calculations for instanceyou can import and use functions coded in python or within these pop ups the current value in the main calculator window is stored in newly opened command-line pop upstoofor use in typed expressions pycalc supports integers (unlimited precision)negativesand floating-point numbers just because python does individual operands and expressions are still evaluated with the eval built-inwhich calls the python parser/interpreter at runtime variable names can be assigned and referenced in the main window with the letter=and "evalkeysthey are assigned in the calculator' namespace dictionary (more complex variable names may be typed in command-line pop upsnote the use of pi in the history windowpycalc preimports names in the math and random modules into the namespace where expressions are evaluated evaluating expressions with stacks now that you have the general idea of what pycalc doesi need to say little bit about how it does what it does most of the changes in this calculator involve managing the expression display and evaluating expressions pycalc is structured as two classesthe calcgui class manages the gui itself it controls input events and is in charge of the main window' display field at the top it doesn' evaluate expressionsthoughfor thatit pycalca calculator program/object