sequencesstringslistsand files curly braces ({}inside the template-string mark "slotsinto which the provided values are inserted the information inside the curly braces tells which value goes in the slot and how the value should be formatted the python formatting operator is very flexiblewe'll cover just some basics hereyou can consult python reference if you' like all of the details in this bookthe slot descriptions will always have the form{:the index tells which of the parameters is inserted into the slot as usual in pythonindexing starts with in the example abovethere is single slot and the index is used to say that the first (and onlyparameter is inserted into that slot the part of the description after the colon specifies how the value should look when it is inserted into the slot again returning to the examplethe format specifier is the format of this specifier is the width specifies how many "spacesthe value should take up if the value takes up less than the specified widthit is space is padded (by default with the space characterif the value requires more space than allottedit will take as much space as is required to show the value so putting here essentially says "use as much space as you need the precision is which tells python to round the value to two decimal places finallythe type character says the value should be displayed as fixed point number that means that the specified number decimal places will always be showneven if they are zero complete description of format specifiers is pretty hairybut you can get good handle on what' possible just by looking at few examples the simplest template strings just specify where to plug in the parameters "hello { { }you may have already won ${ }format("mr ""smith" 'hello mr smithyou may have already won $ oftenyou'll want to control the width and/or precision of numeric value "this int{ : }was placed in field of width format( 'this int was placed in field of width "this int{ : }was placed in field of width format( 'this int was placed in field of width "this float{ : }has width and precision format( 'this float has width and precision "this float{ : }is fixed at decimal placesformat( 'this float is fixed at decimal places"this float{ : }has width and precision format( as of python the index portion of the slot description is optional when the indexes are omittedthe parameters are just filled into the slots in left-to-right fashion