Optional argument of [if]. It's usually good style to omit the
''then'' itself, but can aid clarity when using multi-line
expressions. Compare with [else].

 if {$some_long_and_complex_condition
     && $some_other_condition_making_it_even_longer
 } then {
      # do the right thing here
 } else {
      # do the other right thing here
 }
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[wdb] In my humble opinion, clarity matters always, such that I personally count the usage of ''then'' to the list of ''good style''. But, of course, that's my personal taste. I suppose that usage of ''then'' does not impact the perfomance.

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[Category Command] | [Category Control Structure]