basic constructions will be understood by python as first compute the expressionthen send the result back ( returnto where the function was called from both def and return are reserved words the function depends on ti one variable (or we say that it takes one argument or input parameter)the value of which must be provided when the function is called what actually happens when python meets this codethe def line just tells python that here is function with name and it has one argument python does not look into the function at this stage (except that it checks the code for syntax errorswhen python later on meets the statement print (time)it recognizes function call (timeand recalls that there is function defined with one argument the value of time is then transferred to the (tfunction such that time becomes the first action in the function then python executes one line at time in the function in the final linethe arithmetic expression * * * ** is computedresulting in numberand this number (or more preciselythe python object representing the numberreplaces the call (timein the calling code such that the word print now precedes number rather than function call python proceeds with the next line and sets time to new value the next print statement triggers new call to ( )this time is set to the computations are done line by line in the functionand the returned result replaces (timeinstead of writing print (time)we could alternatively have stored the returned result from the function in variableh (timeprint note that when function contains if-elif-else constructionsreturn may be done from within any of the branches this may be illustrated by the following function containing three return statementsdef check_sign( )if return ' is positiveelif return ' is negativeelsereturn ' is zeroremember that only one of the branches is executed for single call on check_ signso depending on the number xthe return may take place from any of the three return alternatives to return at the end or not programmers disagree whether it is good idea to use return inside function where you wantor if there should only be one single return statement at the end of the function the authors of this book emphasize readable code and think that return can be useful in branches as in the example above when the function is short for longer or more complicated functionsit might be better to have