in python plz

Create a function called symMtx (n), with a default argument of 5 , which returns a symmetric matrix of the form [[1,2,3,,n1,n],[2,1,2,,n1,n],[3,2,1,,n1,n], [n,n1,,3,2,1]] and show that for b=symMtx(),b gives: [1,2,3,4,5],[2,1,2,3,4],[3,2,1,2,3],[4,3,2,1,2],[5,4,3,2,1]] Show b= symMtx (5) returns the same result. Finally, show the result for n=7