pub fn children(&self) -> vec::IntoIter<&Symbol> {
        use self::Terminator::*;
        let mut vars = vec![];
        match *self {
            Branch { ref cond, .. } => {
                vars.push(cond);
            }
            ProgramReturn(ref sym) => {
                vars.push(sym);
            }
            EndFunction(ref sym) => vars.push(&sym),
            Crash => (),
            JumpBlock(_) => (),
        };
        vars.into_iter()
    }
Returns Symbols that the `Terminator` depends on.
weld/src/sir/mod.rs