Function format_multirange 

pub fn format_multirange(ranges: &[RangeSpan]) -> String

v7.37.5 δ — render a Multirange in PG external form {[a,b),[c,d)}. Empty multirange renders as {}. Each range element is formatted with the same [/(/]/) bracket grammar as scalar Value::Range. RangeSpan carries no kind (it lives on the parent Multirange), so this routes element formatting through format_range_element as Value::Range does.