Function interp_eval 

fn interp_eval(
    positional: &[RValue],
    named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Evaluate an expression in a specified environment.

@param expr expression to evaluate (language object or character string) @param envir environment in which to evaluate (default: calling environment) @return the result of evaluating expr