lib/charset.js
function specify(charset, spec, index) {
  var s = 0;
  if(spec.charset.toLowerCase() === charset.toLowerCase()){
    s |= 1;
  } else if (spec.charset !== '*' ) {
    return null
  }

  return {
    i: index,
    o: spec.i,
    q: spec.q,
    s: s
  }
}
function specify(charset, spec, index) {
  var s = 0;
  if(spec.charset.toLowerCase() === charset.toLowerCase()){
    s |= 1;
  } else if (spec.charset !== '*' ) {
    return null
  }

  return {
    i: index,
    o: spec.i,
    q: spec.q,
    s: s
  }
}
Get the specificity of the charset.
@private