gnus-atomic-progn
gnus-atomic-progn is a Lisp macro in `gnus-util.el
'.
(gnus-atomic-progn &rest FORMS)
Evaluate FORMS atomically, which means to protect the evaluation
from being interrupted by the user. An error from the forms themselves
will return without finishing the operation. Since interrupts from
the user are disabled, it is recommended that only the most minimal
operations are performed by FORMS. If you wish to assign many
complicated values atomically, compute the results into temporary
variables and then do only the assignment atomically.