Add the prefix for Source's show_format.

tui_rsync/models/models.py

@@ -110,7 +110,7 @@ class Source(BaseModel):
     def __repr__(self) -> str:
         return f"{self.label}"
 
-    def show_format(self) -> str:
+    def show_format(self, prefix='') -> str:
         output = f"[b]label:[/] {self.label}\n" \
                  f"[b]source:[/] {self.source.path}\n" \
                  f"[b]args:[/] {self.args}\n" \
@@ -119,6 +119,10 @@ class Source(BaseModel):
         for destination in self.destinations:
             output+=f"\t{destination.path}\n"
 
+        if prefix != '':
+            keepends = True
+            output = prefix + f'{prefix}'.join(output.splitlines(keepends))
+
         return output
 
 class Destination(BaseModel):