Query regarding definition of wd_this->wd_cpuse

Hello

I am having very basic query . As we used method "wd_cpuse_*" for component usage . This method is called by using the "wd_this" but I an unable to figure out the class containing the implementation of this method . As "if_wd_component_usage" is the interface and contains the definition only.

data: l_ref_cmp_usage type ref to if_wd_component_usage.

l_ref_cmp_usage = wd_this->wd_cpuse_alv( ).

Thanks

Sandeep