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##### if Statement

This statement has the following look:

    if boolean_expression then
      statement

or with an alternative statement:

    if boolean_expression then
      statement1
    else
      statement2

The `if` ... `then` statement consists of a boolean expression and a statement, which is conditionally executed if the evaluation of boolean_expression yields true.

If `if` ... `then` ... `else` is concerned, statement1 is executed depending on boolean_expression being true, otherwise statement2 is executed alternatively. Note: the statement before else must not finish with a semicolon.