main prompt the and prompt strings can also be changed (they are available in the built-in module sys)but 'll assume they have not been in the book' example listings terminate compound statements at the interactive prompt with blank line at the interactive promptinserting blank line (by hitting the enter key at the start of lineis necessary to tell interactive python that you're done typing the multiline statement that isyou must press enter twice to make compound statement run by contrastblank lines are not required in files and are simply ignored if present if you don' press enter twice at the end of compound statement when working interactivelyyou'll appear to be stuck in limbo statebecause the interactive interpreter will do nothing at all--it' waiting for you to press enter againthe interactive prompt runs one statement at time at the interactive promptyou must run one statement to completion before typing another this is natural for simple statementsbecause pressing the enter key runs the statement entered for compound statementsthoughremember that you must submit blank line to terminate the statement and make it run before you can type the next statement entering multiline statements at the risk of repeating myselfi've received multiple emails from readers who' gotten burned by the last two pointsso they probably merit emphasis 'll introduce multiline ( compoundstatements in the next and we'll explore their syntax more formally later in this book because their behavior differs slightly in files and at the interactive promptthoughtwo cautions are in order here firstbe sure to terminate multiline compound statements like for loops and if tests at the interactive prompt with blank line in other wordsyou must press the enter key twiceto terminate the whole multiline statement and then make it run for example (pun not intended)for in 'spam'print(xpress enter twice here to make this loop run you don' need the blank line after compound statements in script filethoughthis is required only at the interactive prompt in fileblank lines are not required and are simply ignored when presentat the interactive promptthey terminate multiline statements reminderthe continuation line prompt in the preceding is printed by python automatically as visual guideit may not appear in your interface ( idle)and is sometimes omitted by this bookbut do not type it yourself if it' absent also bear in mind that the interactive prompt runs just one statement at timeyou must press enter twice to run loop or other multiline statement before you can type the next statementthe interactive prompt