anchor.diff:      -- +.objectName
       -- +.[  renameTo
               addColumn
  +            dropErr
           ]
       -|> fun table alteration -> { Table = table; Alteration = alteration }
   
  
positive.code:             AsSelect = asSelect
          }
  
  let private ifExists =
      %[  %% kw "IF" -- kw "EXISTS" -|> true
          preturn false
      ]
  
  let private dropObjectType =
      %[  %% kw "INDEX" -|> DropIndex
          %% kw "TABLE" -|> DropTable
  
negative.code:             Name = name
              As = createAs
          }
  
  let private beginStmt =
      %% kw "BEGIN"
  