pub fn difference(&self, other: &Alphabet) -> Self {
        return Alphabet {
            symbols: self.symbols.difference(&other.symbols).collect(),
        };
    }
/// Return a new alphabet taking the difference between this and other.
///
/// # Example
/// ```
/// use bio::alphabets;
///
/// let dna_alphabet = alphabets::Alphabet::new(b"acgtACGT");
/// let dna_alphabet_upper = alphabets::Alphabet::new(b"ACGT");
/// let dna_lower = dna_alphabet.difference(&dna_alphabet_upper);
///
/// assert_eq!(dna_lower, alphabets::Alphabet::new(b"atcg"));
/// ```
Return a new alphabet taking the difference between this and other.
Return a new alphabet taking the difference between this and other .
pub fn difference(&self, other: &Alphabet) -> Self {
        return Alphabet {
            symbols: self.symbols.difference(&other.symbols).collect(),
        };
    }
pub fn difference ( & self , other : & Alphabet ) -> Self { return Alphabet { symbols : self . symbols . difference ( & other . symbols ) . collect ( ) , } ; }
Return a new alphabet taking the difference between this and other.
Return a new alphabet taking the difference between this and other .
&self
other
&Alphabet
&self
other
&Alphabet
example
```
use bio::alphabets.

let dna_alphabet = alphabets::Alphabet::new(b"acgtACGT");
let dna_alphabet_upper = alphabets::Alphabet::new(b"ACGT");
let dna_lower = dna_alphabet.difference(&dna_alphabet_upper).

assert_eq!(dna_lower, alphabets::Alphabet::new(b"atcg"));
```
` ` ` use bio :: alphabets . let dna_alphabet = alphabets :: Alphabet :: new ( b " acgtACGT " ) ; let dna_alphabet_upper = alphabets :: Alphabet :: new ( b " ACGT " ) ; let dna_lower = dna_alphabet . difference ( &dna_alphabet_upper ) . assert_eq! ( dna_lower alphabets :: Alphabet :: new ( b " atcg " )) ; ` ` `