IF(is-this-true?, then-do-this, else-do-this)
IF() chooses to evaluate one of two expressions (then-do-this or else-do-this) according to the an initial condition (is-this-true?, a Yes/No value) and returns the result. Each of the result expressions should produce a value of the same type.
If is-this-true? is TRUE, the result of evaluating then-do-this; otherwise, the result of evaluating else-do-this.