@Override
    public Object createValue(String literal, ValidationContext context) {
        return literal;
    }
Implements strict string equality semantics by returning <code>literal</code> 
itself.
@param literal the value (get returned)
@param context ignored
@return the <code>literal</code> that was passed in
@see org.relaxng.datatype.Datatype#createValue(java.lang.String, org.relaxng.datatype.ValidationContext)
src/nu/validator/datatype/AbstractDatatype.java