Function rexl::interpolate::dollar

pub fn dollar(
    s: &str, 
    named: &HashMap<String, String>, 
    positional: &Vec<String>, 
    default_value: Option<&str>
) -> Result<String, InterpolationError>

! string interpolation by dollar sign [$][a-zA-Z0-9]+ and [$]{[a-zA-Z0-9]+:.*} is supported Example: $x_y_z_1, the variable is x_y_z_1, and has no default value ${x_y_z_1:the_default_value}, the variable is x_y_z_1, and default is: the_default_value ${{:}\:{:}\}, the variable is {:}, and default is {:}\