The if command evaluates active_members [LB::server pool] as an expression (in the same way that expr evaluates its argument). The value of the expression must be a boolean (a numeric value, where 0 is false and anything is true, or a string value such as true or yes for true and false or no for false); if it is true then body1 is executed by passing it to the Tcl interpreter. Otherwise expr2 is evaluated as an expression and if it is true then body2 is executed, and so on.
Without if i don't granular options available.