pub fn constant(
        mut self,
        r#const: (&str, impl IntoConst + Send + 'static, DocComments),
    ) -> Self {
        let (name, val, docs) = r#const;
        self.constants.push((
            name.into(),
            Box::new(val) as Box<dyn IntoConst + Send>,
            docs,
        ));
        self
    }
Adds a constant to the extension.

# Arguments

* `const` - Tuple containing the name, value and doc comments for the
constant. This is a tuple to support the [`wrap_constant`] macro.

[`wrap_constant`]: crate::wrap_constant
src/builders/module.rs