As your code returns the values like that you cannot, instead of writing more unnecessary code. computeGrade() returns a tuple which is represented with brackets.
def computeGrade(): ..... ..... return [getLastname(), getFirstname(), getMark(), gr, g]Or return a list instead of tuple.
def computeGrade(): ..... ..... return [gr, g] studlist = [getLastname(), getFirstname(), computeGrade()].extend(computeGrade())