code: public String getString(String attrName) {
          Object val = attributes.get(attrName);
          return valToString(val);
      }
docs: Returns the value of the specified attribute in the current item as a
  string; or null if the attribute either doesn't exist or the attribute
  value is null.
  
  @see #isNull(String) #isNull(String) to check if the attribute value is
  null.
  @see #isPresent(String) #isPresent(String) to check if the attribute
  value is present.