sub myRunmodeA
{
my $self = shift;
my $isOK = blah (foo, bar)
...
}

sub myRunmodeB
{
my $self = shift;
fixBlahProblem();
...
}

sub blah
{
return if param('problem') eq 'true';
}


##</code><code>##

sub myRunmodeA
{
my $self = shift;
if( blah (foo, bar) )
    {
    #usual code
    }
else
    { return $self->myRunmodeB; }
}