CreateQuery funnel_test_non_null (children 3)
 Identifier funnel_test_non_null
 Columns definition (children 1)
  ExpressionList (children 4)
   ColumnDeclaration dt (children 1)
    DataType DateTime
   ColumnDeclaration u (children 1)
    DataType int
   ColumnDeclaration a (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType String
   ColumnDeclaration b (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType String
 Storage definition (children 3)
  Function MergeTree (children 1)
   ExpressionList
  Identifier dt
  Identifier u