Class ResidualError

              object --+                    
                       |                    
exceptions.BaseException --+                
                           |                
        exceptions.Exception --+            
                               |            
        exceptions.StandardError --+        
                                   |        
               exceptions.ValueError --+    
                                       |    
                      errors._ValueError --+
                                           |
                                          ResidualError

Error raised for a division, power or root operation of an Fsum instance with a residual ratio exceeding the RESIDUAL threshold.