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