my $scalar = $untied_var1 <op> $untied_var2;
my $scalar = func1() <op> $untied_var;
my $scalar = $untied_var <op> func1();

##</code><code>##

my $scalar = func1() <op> func2();
my $scalar = $tied_var1 <op> $tied_var2;
my $scalar = $tied_var <op> func1();
my $scalar = func1() <op> $tied_var;
my $scalar = $obj1->method() <op> $obj2->method();
# and all the other combinations