CreateQuery lc (children 3)
 Identifier lc
 Columns definition (children 1)
  ExpressionList (children 2)
   ColumnDeclaration a (children 1)
    DataType LowCardinality (children 1)
     ExpressionList (children 1)
      DataType Nullable (children 1)
       ExpressionList (children 1)
        DataType String
   ColumnDeclaration b (children 1)
    DataType LowCardinality (children 1)
     ExpressionList (children 1)
      DataType Nullable (children 1)
       ExpressionList (children 1)
        DataType String
 Storage definition (children 2)
  Function MergeTree
  Function tuple (children 1)
   ExpressionList