Function precompile_timezone 

fn precompile_timezone<F>(
    e: &mut MirScalarExpr,
    column_types: &[ReprColumnType],
    build_unary: F,
)
where
    F: FnOnce(Timezone) -> UnaryFunc,

Specializes a binary timezone-applying function call whose timezone argument is a literal. Produces either a unary call with the parsed timezone baked in, or a literal error.