The if control structure executes a process and returns its value if a condition is true, otherwise if the condition is not true, the process is skipped over.
(1) if [condition1] : [process1]
(2) if [condition1] : [process1] else [condition2] : [process2]
(1) The [condition1] value must be a bool, and when [condition1] is true, [process1] is executed and returned, otherwise the null value is returned
(2) Like (1), except when [condition1] is true, the else clauses are ignored after [process1], otherwise the else clauses are executed. else clauses can be chained. If [condition1] is false, [condition2] is checked for each clause, and the first clause to have [condition2] to evaluate to true is executed and returned. All other else clauses are ignored. [condition2] can be omitted and will default to true, but such an else clause must be placed last. The null value is returned if no clause executes.