pub fn cause(&self) -> Option<&self::Error> {
        // match self.cause {
        //     Some(ref bc) => Some(&*bc),
        //     None => None,
        // }
        self.cause.as_ref().map(|c| &**c)
    }
/// Returns the immediate cause of this error (e.g. the next error in the
/// chain).
Returns the immediate cause of this error .
Returns the immediate cause of this error .
pub fn cause(&self) -> Option<&self::Error> {
        // match self.cause {
        //     Some(ref bc) => Some(&*bc),
        //     None => None,
        // }
        self.cause.as_ref().map(|c| &**c)
    }
pub fn cause ( & self ) -> Option < & self :: Error > { // match self.cause { //     Some(ref bc) => Some(&*bc), //     None => None, // } self . cause . as_ref ( ) . map ( | c | & * * c ) }
Returns the immediate cause of this error (e.g.
Returns the immediate cause of this error ( e . g .
&self
&self