Redef!
A common way to set ld-redefinition-action
Example and General Form:
ACL2 !>:redef!
This command sets ld-redefinition-action to '(:warn!
. :overwrite).
This command allows redefinition of functions and other events
without undoing, but with a warning. The command :redef is
similar, but queries the user first before doing the redefinition. For more
options and an important warning about the danger of using redefinition,
including possible unsoundness, see ld-redefinition-action.