src/main/java/com/github/fge/grappa/support/Characters.java
public static Characters of(final String chars)
    {
        return chars.isEmpty() ? NONE : of(chars.toCharArray());
    }
public static Characters of(final String chars)
    {
        return chars.isEmpty() ? NONE : of(chars.toCharArray());
    }
Creates a new Characters instance containing only the given chars.

@param chars the chars
@return a new Characters object