use Carp qw(croak);
  use Scalar::Util qw(blessed);
  
  sub htmlprint {
    my %arg = @_;
    exists $arg{file}   or croak "Expected file";
    exists $arg{text}   or croak "Expected text";
    exists $arg{colour} or croak "Expected colour";
    
    ref($arg{file}) eq 'GLOB'
      or blessed($arg{file}) && $arg{file}->can('printf')
      or croak "File should be a filehandle or object";
    
    defined($arg{text} && !ref($arg{text})
      or croak "Text should be a string";
    
    defined($arg{colour} && !ref($arg{colour})
      or croak "Colour should be a string";
    
    $arg{file}->printf(
      '<span style="color:%s">%s</span>',
      $arg{colour},
      $arg{text},
    );
  }