sub _macro_map {                                                                                                                                                                    
  my $prefix = shift;                                                                                                                                                             
  map {                                                                                                                                                                              
     my ($key) = /^(?:$prefix)(.*)/ or die "_macro_map: $_";                                                                                                                                                                                                                                                                                     
     no strict 'refs';                                                                                                                                                               
     ( $key => &$_ )                                                                                                                                                             
    } @_;                                                                                                                                                                       
}