Panku produces compilation erros, please add static typization

[smedelyan]

Describe the bug

Aside from having some parts of panku code less readable than they could be, this produces compilation errors for some types (e.g. row_ui_color.gd:6 redeclares return type which differs from parent's Variant which, in turn, is auto-evaluated by compiler because return type is not set at all...)

[vegechick123]

In my experiments,adding a variant type hint explicitly to the parent class function will fix the issue.