When I check the types of fields in a data structure, I found most
fields are defined as general types, as List, Node. Then, To know the
content inside the List, I need to track the usage of the fields.
For example, the fromClause in SelectStmt is defined as List. And, the
content in the ListCell is with the type of RangeVar.
Is there other easier way to check the types information, rather than
track through the code?
Or is there any document about it?