typeface typewriter font emphasized bold normal text meaning text to be written verbatim place where you can use an arbitrary expression place where you can use an arbitrary identifier description of what goes in that positionwithout giving explicit syntax if there are several variations on particular part of the syntaxalternatives will be show on successive lines to emphasize the successive parts of the syntaxspace will generally be left around symbol and punctuation charactersbut the space is not required in actual use python shell (aa shell window may be opened in idle run python shell [windows in idle (page )(bentering commandsi commands may be entered at the prompt [addition and subtraction (page )ii if the shell detects that command is not finished at the end of the linea continuation line is shown with no [multiplicationparenthesesand precedence (page )iii statements with heading ending in colon followed by an indented blockmust be terminated with an empty line [basic for loops (page )iv the shell evaluates completed command immediatelydisplaying any result other than nonestarting on the next line [addition and subtraction (page ) the shell remembers variable and function names [variables and assignment (page )(can earlier shell line may to copied and edited by clicking anywhere in the previously displayed line and then pressing enter idle editing (astart new window from the file menu by selecting newopen or recent files [loading program in the idle editorand running it (page )(bmake your python file names end with py[literals and identifiers (page ) to run program from an idle editor window(aselect run -run module or press function key the program runs in the shell windowafter resetting the shell so all old names are forgotten [loading program in the idle editorand running it (page ) if the program is expecting keyboard inputthe text cursor should appear at the end of the shell history if you somehow move the cursor elsewhereyou must explicitly move it back [the idle editor and execution (page )ii press ctrl- to stop running program in long or infinite loop iii after program terminatesthe shell remembers function definitions and variable names define outside of any function [ first function definition (page ) errors come in three categories(asyntax errorstext that the interpreter recognizes as illegal when first reading it this prevents execution of your code python lets you know where it realized there was an error sometimes this is the exact locationbut the actual error could be anywhere earlieroften on the previous line [variables and assignment (page )(bexecution errorsthe first illegal action is detected while running your command or program the source of the error could be in the line where execution failsor it could be an earlier logical error that only later forces an execution error [variables and assignment (page )execution errors generate traceback [function parameters (page ) summary