SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 3)
    Function covarPop (children 1)
     ExpressionList (children 2)
      Identifier a
      Identifier a
    Function covarPop (children 1)
     ExpressionList (children 2)
      Identifier b
      Identifier b
    Function covarPop (children 1)
     ExpressionList (children 2)
      Identifier c
      Identifier c
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier decimal