diff --git a/pyWebLayout/abstract/block.py b/pyWebLayout/abstract/block.py
index 2b28aa6..4f3bf87 100644
--- a/pyWebLayout/abstract/block.py
+++ b/pyWebLayout/abstract/block.py
@@ -99,8 +99,8 @@ class Paragraph(Styleable, FontRegistry, Block):
             container.add_block(paragraph)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return paragraph
 
@@ -251,8 +251,8 @@ class Heading(Paragraph):
             container.add_block(heading)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return heading
 
@@ -313,8 +313,8 @@ class Quote(Block):
             container.add_block(quote)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return quote
 
@@ -416,8 +416,8 @@ class CodeBlock(Block):
             container.add_block(code_block)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return code_block
 
@@ -516,8 +516,8 @@ class HList(Block):
             container.add_block(hlist)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return hlist
 
@@ -633,8 +633,8 @@ class ListItem(Block):
             container.add_item(item)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_item' method")
+                f"Container {type(container).__name__} must have an 'add_item' method"
+            )
 
         return item
 
@@ -766,8 +766,8 @@ class TableCell(Block):
             container.add_cell(cell)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_cell' method")
+                f"Container {type(container).__name__} must have an 'add_cell' method"
+            )
 
         return cell
 
@@ -909,8 +909,8 @@ class TableRow(Block):
             container.add_row(row, section)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_row' method")
+                f"Container {type(container).__name__} must have an 'add_row' method"
+            )
 
         return row
 
@@ -1025,8 +1025,8 @@ class Table(Block):
             container.add_block(table)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return table
 
@@ -1193,8 +1193,8 @@ class Image(Block):
             container.add_block(image)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return image
 
@@ -1567,8 +1567,8 @@ class HorizontalRule(Block):
             container.add_block(hr)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return hr
 
@@ -1608,7 +1608,7 @@ class PageBreak(Block):
             container.add_block(page_break)
         else:
             raise AttributeError(
-                f"Container {
-                    type(container).__name__} must have an 'add_block' method")
+                f"Container {type(container).__name__} must have an 'add_block' method"
+            )
 
         return page_break