code: func (constraints *tokenConstraints) validAudience(aud ast.Value) (valid bool) {
  	var ok bool
  	var s ast.String
  	if s, ok = aud.(ast.String); ok {
  		return string(s) == constraints.aud
  	}
  	var a ast.Array
  	if a, ok = aud.(ast.Array); ok {
  		for _, t := range a {
  			if s, ok = t.Value.(ast.String); ok {
  				if string(s) == constraints.aud {
  					return true
  				}
  			} else {
  				// Ill-formed aud claim
  				return false
  			}
  		}
  	}
  	return false
  }
docs: // validAudience checks the audience of the JWT.
  // It returns true if it meets the constraints and false otherwise.