How can I know what the variables in the code refer to?

[Liyuansongdsb]

I studied the paper of mamba and got this code. but I still do not know how to implement it. Because I cannot understand what mean the variable in the code refers to, just like "d_model", "expand".... How should I learn this code? Should I learn the code of H3 or SSM? Hope to get your help.