default values are used hello [ true somefunc('hello'[ , ]'hi'hello [ hi kwarg has default value somefunc('hello'[ , ]'hi' hello [ hi kwarg has default value somefunc('hello'[ , ]kwarg ='hi'#kwarg hello [ true hi kwarg has default value somefunc('hello'[ , ]kwarg ='hi'kwarg = hello [ hi specify all args using what we now know about default argumentswe can improve the function considered abovewhich implements the formula (tv gt hereit could be natural to think of as the primary argument to the functionwhich should always be providedwhile and possibly also could be provided as default arguments the function definition in python could read def yfunc(tv = = ) * * * ** dydt * return ydydt #example callsy dy yfunc( dy yfunc( , = dy yfunc( , , documentation of python functions an important python convention is to document the purpose of functionits argumentsand its return values in doc string (triple-quotedstring written immediately after the function header the doc string can be long or shortdepending on the complexity of the function and its inputs and outputs the following two examples show how doc string can be useddef amount(prn)"""compute the growth of an investment over time "" *( + / )** return def line( )""compute the coefficients and in the mathematical expression for straight line * that goes through two points ( and ( point on the line (floats