Trying to add borders to a table to save as .txt

So i have 3 lists, which I am trying to make into a table. Initially I just used T=table(x,y,z), but this was not aligned and had no borders. So now I am trying to set up the table first with borders, then append the lists to the table. I am getting this error message and I have no idea to solve it, and am struggling to find any other way to make a table with borders.

Thanks in advance

"Error using append (line 38) Wrong number of input arguments for obsolete matrix-based syntax."

if true
function example()
import mlreportgen.dom.*;
table = Table(3);
table.Style = {Border('inset','red','3px'), ...
             ColSep('single','green','1px'), ...
             RowSep('single','green','1px')};
table.Width = '50%';
x={'a';'b';'c'}
y=[1;2;3]
z=[4;5;6]
%T=table(x,y,z)
%append(T,table)
append({x,y,z},table)
%writetable(T,'mydata.txt')
end
end