module RuboCop::Cop::AccessModifierNode

def class_or_module_parent?(node)

named private, protected or public.
is a Class or Module. Filters out simple method calls to similarly
Returns true when the parent of what looks like an access modifier 
def class_or_module_parent?(node)
  node.each_ancestor do |ancestor|
    if ancestor.block_type?
      return true if ancestor.class_constructor?
    elsif !ancestor.begin_type?
      return [:casgn, :sclass, :class, :module].include?(ancestor.type)
    end
  end
end

def modifier_node?(node)

Returns true when the node is an access modifier. 
def modifier_node?(node)
  modifier_structure?(node) && class_or_module_parent?(node)
end

def modifier_structure?(node)

Returns true when the node looks like an access modifier. 
def modifier_structure?(node)
  private_node?(node) ||
    protected_node?(node) ||
    public_node?(node) ||
    module_function_node?(node)
end