pub fn i(&self) -> Result<i64, SexpError> {
        let s = self.string()?;
        let i = s.parse()?;
        Ok(i)
    }
/// access the symbolic-expression as if it is a String
/// that is an i64
access the symbolic-expression as if it is a String
that is an i64
access the symbolic - expression as if it is a String that is an i64
pub fn i(&self) -> Result<i64, SexpError> {
        let s = self.string()?;
        let i = s.parse()?;
        Ok(i)
    }
pub fn i ( & self ) -> Result < i64 , SexpError > { let s = self . string ( ) ? ; let i = s . parse ( ) ? ; Ok ( i ) }
access the symbolic-expression as if it is a String
that is an i64
access the symbolic - expression as if it is a String that is an i64
&self