Documentation improvement: Can Node be null?

Dear LibAdaLang developers,

Libadalang is nicely documented.
For example, the function F_Suffix is documented in libadalang-analysis.adsas follows

   function F_Suffix
     (Node : Call_Expr'Class) return Ada_Node;
   --  This field can contain one of the following nodes:
   --  :ada:ref:`Attribute_Ref`, :ada:ref:`Basic_Assoc_List`,
   --  :ada:ref:`Bin_Op`, :ada:ref:`Call_Expr`, :ada:ref:`Char_Literal`,
   --  :ada:ref:`Discrete_Subtype_Indication`, :ada:ref:`Dotted_Name`,
   --  :ada:ref:`Explicit_Deref`, :ada:ref:`Identifier`, :ada:ref:`Qual_Expr`,
   --  :ada:ref:`Reduce_Attribute_Ref`, :ada:ref:`String_Literal`,
   --  :ada:ref:`Target_Name`, :ada:ref:`Update_Attribute_Ref`
   --% belongs-to: Call_Expr

Yet, I think there is room for improvement.

Suppose, I want to call Kind on the result of X.F_Suffix.
Kind requires that for its argument Y holds that Y.Is_Null returns false.

However, the documentation of F_Suffix states nothing about whether the node returned by F_Suffix can be null.
So, it is unclear whether a check like not X.F_Suffix.Is_Null is

• necessary before calling Kind or
• just hampering performance and wasting energy?

Can the documentation be extended with information about an Ada_Node being a nullnode?

Greetings,
Pierre

Start in libadalang-analysis.ads with the F_Suffix declaration and its referenced Kind contract. Determine how the documentation represents whether an Ada_Node may be null, then document the nullability of F_Suffix clearly, including when callers must check Is_Null. Done means users can tell whether calling Kind directly is valid.