return the name of the argument . if the option does not take an argument , returns null . concode_field_sep String argumentName concode_elem_sep boolean joined concode_elem_sep String description concode_elem_sep char shortName concode_elem_sep String longName concode_field_sep boolean getTakesArgument concode_elem_sep char getShortName concode_elem_sep void parsed concode_elem_sep String getDescription concode_elem_sep String getLongName concode_elem_sep boolean isJoined
String function ( ) { return argumentName ; }