How to access register in a model when sub blcok is of type uvm_reg_fille?

My register model has sub block (let us say instance “foo”) of type uvm_reg_file. This sub-block has several registers of type uvm_register. I have a handle to register model.

T_foo extends uvm_reg_file;

Any_reg register_name;

endclass

r_block extends uvm_reg_block;
rand T_foo foo;

endclass

r_block handle_to_model;

How do I access register in sub-block “foo”?

When I access with handle_to_model.foo.register_name, I get error that foo is not a class item.

How do you access uvm_reg_file instance from register model? Do you have any examples?