key backs up one level of indentationand you can customize how far to the right idle indents statements in nested block there is no universal standard on thisfour spaces or one tab per level is commonbut it' generally up to you to decide how and how much you wish to indent (unless you work at company that' endured politics and manuals to standardize this tooindent further to the right for further nested blocksand less to close the prior block as rule of thumbyou probably shouldn' mix tabs and spaces in the same block in pythonunless you do so consistentlyuse tabs or spaces in given blockbut not both (in factpython now issues an error for inconsistent use of tabs and spacesas we'll see in then againyou probably shouldn' mix tabs or spaces in indentation in any structured language--such code can cause major readability issues if the next programmer has his or her editor set to display tabs differently than yours -like languages might let coders get away with thisbut they shouldn'tthe result can be mangled mess regardless of which language you code inyou should be indenting consistently for readability in factif you weren' taught to do this earlier in your careeryour teachers did you disservice most programmers--especially those who must read otherscode --consider it major asset that python elevates this to the level of syntax moreovergenerating tabs instead of braces is no more difficult in practice for tools that must output python code in generalif you do what you should be doing in -like language anyhowbut get rid of the bracesyour code will satisfy python' syntax rules few special cases as mentioned previouslyin python' syntax modelthe end of line terminates the statement on that line (without semicolonsnested statements are blocked and associated by their physical indentation (without bracesthose rules cover almost all python code you'll write or see in practice howeverpython also provides some special-purpose rules that allow customization of both statements and nested statement blocks they're not required and should be used sparinglybut programmers have found them useful in practice statement rule special cases although statements normally appear one per lineit is possible to squeeze more than one statement onto single line in python by separating them with semicolonsa print( bthree statements on one line this is the only place in python where semicolons are requiredas statement separators this only worksthoughif the statements thus combined are not themselves tale of two ifs