Have a look at < and { command family, IIRC you can tell them what to do for each prompt while stepping thru code

update

 DB<1> h >
 ?            List Perl commands to run after each prompt.
 expr        Define Perl command to run after each prompt.
> expr        Add to the list of Perl commands to run after each promp
+t.
 *        Delete the list of Perl commands to run after each prompt.
 DB<2> h }
 is not a debugger command.
 DB<3> h {
 db_command    Define debugger command to run before each prompt.
 ?            List debugger commands to run before each prompt.
{ db_command    Add to the list of debugger commands to run before eac
+h prompt.
 *             Delete the list of debugger commands to run before each
+ prompt.
 DB<4> h <
 ?            List Perl commands to run before each prompt.
 expr        Define Perl command to run before each prompt.
< expr        Add to the list of Perl commands to run before each prom
+pt.
 *                Delete the list of perl commands to run before each 
+prompt.
 DB<5>
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"Perl commands" => Perl code

"debugger commands" => those one letter commands listed with h h