diff --git a/cell_test.go b/cell_test.go
index 1efbc5a..60f8751 100644
--- a/cell_test.go
+++ b/cell_test.go
@@ -110,7 +110,7 @@ func ExampleFile_SetCellFloat() {
 	f := NewFile()
 	var x = 3.14159265
 	if err := f.SetCellFloat("Sheet1", "A1", x, 2, 64); err != nil {
-		fmt.Println(err)
+		println(err.Error())
 	}
 	val, _ := f.GetCellValue("Sheet1", "A1")
 	fmt.Println(val)
diff --git a/excelize_test.go b/excelize_test.go
index ea82828..c7f5cad 100644
--- a/excelize_test.go
+++ b/excelize_test.go
@@ -1259,7 +1259,7 @@ func fillCells(f *File, sheet string, colCount, rowCount int) {
 		for row := 1; row <= rowCount; row++ {
 			cell, _ := CoordinatesToCellName(col, row)
 			if err := f.SetCellStr(sheet, cell, cell); err != nil {
-				panic(err)
+				println(err.Error())
 			}
 		}
 	}
diff --git a/file_test.go b/file_test.go
index 97ff720..8c5050c 100644
--- a/file_test.go
+++ b/file_test.go
@@ -12,18 +12,17 @@ func BenchmarkWrite(b *testing.B) {
 			for col := 1; col <= 20; col++ {
 				val, err := CoordinatesToCellName(col, row)
 				if err != nil {
-					panic(err)
+					b.Error(err)
 				}
 				if err := f.SetCellDefault("Sheet1", val, s); err != nil {
-					panic(err)
+					b.Error(err)
 				}
 			}
 		}
 		// Save xlsx file by the given path.
 		err := f.SaveAs("./test.xlsx")
 		if err != nil {
-			panic(err)
+			b.Error(err)
 		}
 	}
-
 }
diff --git a/cellmerged.go b/merge.go
similarity index 100%
rename from cellmerged.go
rename to merge.go
diff --git a/cellmerged_test.go b/merge_test.go
similarity index 100%
rename from cellmerged_test.go
rename to merge_test.go
diff --git a/rows.go b/rows.go
index d24b1a6..40972ae 100644
--- a/rows.go
+++ b/rows.go
@@ -63,7 +63,6 @@ type Rows struct {
 	err                        error
 	curRow, totalRow, stashRow int
 	sheet                      string
-	stashColumn                []string
 	rows                       []xlsxRow
 	f                          *File
 	decoder                    *xml.Decoder
@@ -111,7 +110,6 @@ func (rows *Rows) Columns() ([]string, error) {
 						}
 						if row > rows.curRow {
 							rows.stashRow = row - 1
-							rows.stashColumn = columns
 							return columns, err
 						}
 					}
@@ -153,12 +151,19 @@ func (err ErrSheetNotExist) Error() string {
 // Rows return a rows iterator. For example:
 //
 //    rows, err := f.Rows("Sheet1")
+//    if err != nil {
+//        println(err.Error())
+//        return
+//    }
 //    for rows.Next() {
 //        row, err := rows.Columns()
+//        if err != nil {
+//            println(err.Error())
+//        }
 //        for _, colCell := range row {
-//            fmt.Print(colCell, "\t")
+//            print(colCell, "\t")
 //        }
-//        fmt.Println()
+//        println()
 //    }
 //
 func (f *File) Rows(sheet string) (*Rows, error) {
diff --git a/rows_test.go b/rows_test.go
index 1127bb1..9377d5e 100644
--- a/rows_test.go
+++ b/rows_test.go
@@ -143,6 +143,7 @@ func TestColumns(t *testing.T) {
 	rows.decoder = f.xmlNewDecoder(bytes.NewReader([]byte(`<worksheet><sheetData><row r="2"><c r="A1" t="s"><v>1</v></c></row></sheetData></worksheet>`)))
 	rows.curRow = 1
 	_, err = rows.Columns()
+	assert.NoError(t, err)
 
 	rows.decoder = f.xmlNewDecoder(bytes.NewReader([]byte(`<worksheet><sheetData><row r="A"><c r="A1" t="s"><v>1</v></c></row><row r="A"><c r="2" t="str"><v>B</v></c></row></sheetData></worksheet>`)))
 	rows.stashRow, rows.curRow = 0, 1
diff --git a/sheet.go b/sheet.go
index 2654b8f..19b90c6 100644
--- a/sheet.go
+++ b/sheet.go
@@ -339,12 +339,12 @@ func (f *File) GetSheetIndex(name string) int {
 // GetSheetMap provides a function to get worksheet name and index map of XLSX.
 // For example:
 //
-//    f, err := excelize.OpenFile("./Book1.xlsx")
+//    f, err := excelize.OpenFile("Book1.xlsx")
 //    if err != nil {
 //        return
 //    }
 //    for index, name := range f.GetSheetMap() {
-//        fmt.Println(index, name)
+//        println(index, name)
 //    }
 //
 func (f *File) GetSheetMap() map[int]string {
diff --git a/sheet_test.go b/sheet_test.go
index 7a58248..a03066a 100644
--- a/sheet_test.go
+++ b/sheet_test.go
@@ -19,7 +19,7 @@ func ExampleFile_SetPageLayout() {
 		"Sheet1",
 		excelize.PageLayoutOrientation(excelize.OrientationLandscape),
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	if err := f.SetPageLayout(
 		"Sheet1",
@@ -27,7 +27,7 @@ func ExampleFile_SetPageLayout() {
 		excelize.FitToHeight(2),
 		excelize.FitToWidth(2),
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	// Output:
 }
@@ -41,17 +41,17 @@ func ExampleFile_GetPageLayout() {
 		fitToWidth  excelize.FitToWidth
 	)
 	if err := f.GetPageLayout("Sheet1", &orientation); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	if err := f.GetPageLayout("Sheet1", &paperSize); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	if err := f.GetPageLayout("Sheet1", &fitToHeight); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.GetPageLayout("Sheet1", &fitToWidth); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	fmt.Println("Defaults:")
 	fmt.Printf("- orientation: %q\n", orientation)
diff --git a/sheetpr_test.go b/sheetpr_test.go
index d1ae2f1..6a35a6e 100644
--- a/sheetpr_test.go
+++ b/sheetpr_test.go
@@ -40,7 +40,7 @@ func ExampleFile_SetSheetPrOptions() {
 		excelize.AutoPageBreaks(true),
 		excelize.OutlineSummaryBelow(false),
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	// Output:
 }
@@ -66,7 +66,7 @@ func ExampleFile_GetSheetPrOptions() {
 		&autoPageBreaks,
 		&outlineSummaryBelow,
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	fmt.Println("Defaults:")
 	fmt.Printf("- codeName: %q\n", codeName)
@@ -189,7 +189,7 @@ func ExampleFile_SetPageMargins() {
 		excelize.PageMarginRight(1.0),
 		excelize.PageMarginTop(1.0),
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	// Output:
 }
@@ -215,7 +215,7 @@ func ExampleFile_GetPageMargins() {
 		&marginRight,
 		&marginTop,
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 	fmt.Println("Defaults:")
 	fmt.Println("- marginBottom:", marginBottom)
diff --git a/sheetview_test.go b/sheetview_test.go
index e45b8ce..8412002 100644
--- a/sheetview_test.go
+++ b/sheetview_test.go
@@ -47,7 +47,7 @@ func ExampleFile_SetSheetViewOptions() {
 		excelize.ZoomScale(80),
 		excelize.TopLeftCell("C3"),
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	var zoomScale excelize.ZoomScale
@@ -55,22 +55,22 @@ func ExampleFile_SetSheetViewOptions() {
 	fmt.Println("- zoomScale: 80")
 
 	if err := f.SetSheetViewOptions(sheet, 0, excelize.ZoomScale(500)); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.GetSheetViewOptions(sheet, 0, &zoomScale); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	fmt.Println("Used out of range value:")
 	fmt.Println("- zoomScale:", zoomScale)
 
 	if err := f.SetSheetViewOptions(sheet, 0, excelize.ZoomScale(123)); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.GetSheetViewOptions(sheet, 0, &zoomScale); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	fmt.Println("Used correct value:")
@@ -111,7 +111,7 @@ func ExampleFile_GetSheetViewOptions() {
 		&zoomScale,
 		&topLeftCell,
 	); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	fmt.Println("Default:")
@@ -125,27 +125,27 @@ func ExampleFile_GetSheetViewOptions() {
 	fmt.Println("- topLeftCell:", `"`+topLeftCell+`"`)
 
 	if err := f.SetSheetViewOptions(sheet, 0, excelize.TopLeftCell("B2")); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.GetSheetViewOptions(sheet, 0, &topLeftCell); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.SetSheetViewOptions(sheet, 0, excelize.ShowGridLines(false)); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.GetSheetViewOptions(sheet, 0, &showGridLines); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.SetSheetViewOptions(sheet, 0, excelize.ShowZeros(false)); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	if err := f.GetSheetViewOptions(sheet, 0, &showZeros); err != nil {
-		panic(err)
+		println(err.Error())
 	}
 
 	fmt.Println("After change:")
diff --git a/sparkline_test.go b/sparkline_test.go
index dca32e9..45bf386 100644
--- a/sparkline_test.go
+++ b/sparkline_test.go
@@ -298,12 +298,12 @@ func prepareSparklineDataset() *File {
 	f.NewSheet("Sheet3")
 	for row, data := range sheet2 {
 		if err := f.SetSheetRow("Sheet2", fmt.Sprintf("A%d", row+1), &data); err != nil {
-			panic(err)
+			println(err.Error())
 		}
 	}
 	for row, data := range sheet3 {
 		if err := f.SetSheetRow("Sheet3", fmt.Sprintf("A%d", row+1), &data); err != nil {
-			panic(err)
+			println(err.Error())
 		}
 	}
 	return f