Function is_repeatable_condition 

pub fn is_repeatable_condition(expr: &BoundExpr) -> bool

Reports whether a condition may be tested more than once with the same answer each time.

A condition on an outer term can be tested before a lateral join runs its function, so that the function is not called for rows the condition removes. It is tested again with the rest of the WHERE, which is only harmless for a condition with no subquery, no random function and no registered function whose determinism the planner cannot see.

@param expr - the condition