Code before warnings are enabled at line 11, column 1.  See page 431 of PBP.  (Severity: 4)
Return value of "open" ignored at line 87, column 9.  Check the return value of "open" for success.  (Severity: 3)
Return value of "open" ignored at line 113, column 17.  Check the return value of "open" for success.  (Severity: 3)
Return value of "close" ignored at line 120, column 17.  Check the return value of "close" for success.  (Severity: 2)
Return value of "close" ignored at line 126, column 9.  Check the return value of "close" for success.  (Severity: 2)
Comma used to separate statements at line 140, column 5.  See pages 68,71 of PBP.  (Severity: 4)
Expression form of "eval" at line 140, column 10.  See page 161 of PBP.  (Severity: 5)
Comma used to separate statements at line 167, column 9.  See pages 68,71 of PBP.  (Severity: 4)
Comma used to separate statements at line 169, column 9.  See pages 68,71 of PBP.  (Severity: 4)
Comma used to separate statements at line 192, column 5.  See pages 68,71 of PBP.  (Severity: 4)