format-control—a format control.
args—format arguments for format-control.
The function method-combination-error is used to signal an error
in method combination.
The error message is constructed by using a format-control suitable
for format and any args to it. Because an implementation may
need to add additional contextual information to the error message,
method-combination-error should be called only within the
dynamic extent of a method combination function.
Whether method-combination-error returns to its caller or exits
via throw is implementation-dependent.
The debugger might be entered.
*break-on-signals*