anchor.diff:  import PostgreKeyword, DataType, Keyword,BaseRule,Symbol;
   
   createIndex:
  -	CREATE UNIQUE? INDEX CONCURRENTLY? ((IF NOT EXISTS)? indexName)? ON tableName indexType?
  -	keyParts
  -	withStorageParameters?
  +    CREATE UNIQUE? INDEX CONCURRENTLY? ((IF NOT EXISTS)? indexName)? ON tableName indexType?
  +    keyParts
  +    withStorageParameters?
       tableSpaceClause?
       whereClause?
       ;
  
positive.code: 	;
  
  withStorageParameters:
  	WITH LEFT_PAREN storageParameters RIGHT_PAREN
  	;
  
  storageParameters:
  
negative.code:     ;
  
  setStorageParameter:
      SET storageParametersWithParen
      ;
  
  resetStorageParameter:
      RESET storageParametersWithParen
      ;
      
  storageParametersWithParen:
      LEFT_PAREN storageParameters RIGHT_PAREN
      ;
  
  alterIndexDependsOnExtension:
  