Matlab cody does not support lambertw. Try to create a lambert's w function yourself.
Lambert's W is the function that solves
x*exp(x) = A;
given the value of A.
Read more about Lambert's W here.
Though it is not particularly appropriate for this particular function, consider using Newton-Raphson's method. Since all test cases will converge if starting with 0.
The relative tolerance for the result of x*exp(x) compared to A is 1e-5.