REDEF!

system hacker's redefinition command
Major Section:  MISCELLANEOUS

Example and General Form:
ACL2 !>:redef!
ACL2 p!>
This command sets ld-redefinition-action to '(:warn! . :overwrite) sets the default defun-mode to :program, and invokes (set-state-ok t).

This is the ACL2 system hacker's redefinition command. Note that even system functions can be redefined with a mere warning. Be careful!