fn is_fixed(&self) -> Option<&OF> {
        match (&self.lower_bound, &self.upper_bound) {
            (Some(lower), Some(upper)) if lower == upper => Some(lower),
            _ => None,
        }
    }
/// Whether the variable allows only a single value.
///
/// # Return value
///
/// `Some` with the value if so, `None` otherwise.
Whether the variable allows only a single value.
Whether the variable allows only a single value .
fn is_fixed(&self) -> Option<&OF> {
        match (&self.lower_bound, &self.upper_bound) {
            (Some(lower), Some(upper)) if lower == upper => Some(lower),
            _ => None,
        }
    }
fn is_fixed ( & self ) -> Option < & OF > { match ( & self . lower_bound , & self . upper_bound ) { ( Some ( lower ) , Some ( upper ) ) if lower == upper => Some ( lower ) , _ => None , } }
Whether the variable allows only a single value.
Whether the variable allows only a single value .
&self
&self
return value
`Some` with the value if so, `None` otherwise.
` Some ` with the value if so ` None ` otherwise .