

          keylget listvar [key [retvar | {}]]
               Return the value associated with key from the keyed
               list in the variable listvar.  If retvar is not
               specified, then the value will be returned as the
               result of the command. In this case, if key is not
               found in the list, an error will result.

               If retvar is specified and key is in the list, then the
               value is returned in the variable retvar and the
               command returns 1 if the key was present within the
               list.  If key isn't in the list, the command will
               return 0, and retvar will be left unchanged.  If {} is
               specified for retvar, the value is not returned,
               allowing the Tcl programmer to determine if a key is
               present in a keyed list without setting a variable as a
               side-effect.

               If key is omitted, then a list of all the keys in the
               keyed list is returned.
