pub fn opt_str(&self, nm: &str) -> Option<String> {
        match self.opt_val(nm) {
            Some(Val(s)) => Some(s),
            _ => None,
        }
    }
/// Returns the string argument supplied to a matching option or `None`.
Returns the string argument supplied to a matching option or `None`.
Returns the string argument supplied to a matching option or ` None ` .
pub fn opt_str(&self, nm: &str) -> Option<String> {
        match self.opt_val(nm) {
            Some(Val(s)) => Some(s),
            _ => None,
        }
    }
pub fn opt_str ( & self , nm : & str ) -> Option < String > { match self . opt_val ( nm ) { Some ( Val ( s ) ) => Some ( s ) , _ => None , } }
Returns the string argument supplied to a matching option or `None`.
Returns the string argument supplied to a matching option or ` None ` .
&self
nm
&str
&self
nm
&str