Macro molecular_formula 

macro_rules! molecular_formula {
    ($($tail:tt)*) => { ... };
}

Easily define molecular formulas using the following syntax: <element> <num> or [<isotope> <element> <num>]. The spaces are required by the Rust compiler.

molecular_formula!(C 12 [13 C 1] H 24);

Panics

It panics if the defined molecular formula is not valid. A formula is not valid if not existing isotopes are used or if an element is used that does not have a defined molecular weight (does not have natural abundance).