extern crate meval;
fn trim_parenthesis(arg: &str) -> &str { arg.trim_start_matches('(').trim_end_matches(')') }
pub fn maybe_trim_parenthesis(arg: &str) -> &str {
if arg.starts_with('(') && arg.ends_with(')') {
trim_parenthesis(arg)
} else {
arg
}
}
pub fn eval_f64(expr: &str) -> Result<f64, meval::Error> { meval::eval_str(expr) }