You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: is.m
    path of file: ./repos/YALMIP/extras/@ndsdpvar
    
    the code of the file until where you have to start completion: function YESNO = is(X,property,additional)
%IS Check property of variable.
%   d = IS(x,property) returns 1 if 'property' holds

    
function YESNO = is(X,property,additional)
%IS Check property of variable.
%   d = IS(x,property) returns 1 if 'property' holds
%
%   Properties possible to test are: 'complex'

switch property
    case 'complex'
        YESNO = ~isreal(X.basis);
    otherwise
        error('Wrong input argument.');
end