code: public static void setScriptVar(ScriptContext context, String key, String value) {
  		setScriptVarImpl(getScriptName(context), key, value);
  	}
docs: Sets or removes a script variable.
  <p>
  The variable is removed when the {@code value} is {@code null}.
  
  @param context the context of the script.
  @param key the key of the variable.
  @param value the value of the variable.
  @throws IllegalArgumentException if one of the following conditions is met:
  <ul>
  <li>The {@code context} is {@code null} or it does not contain the name of the script;</li>
  <li>The {@code key} is {@code null} or its length is higher than the maximum allowed
  ({@value #MAX_KEY_SIZE});</li>
  <li>The {@code value}'s length is higher than the maximum allowed ({@value #MAX_VALUE_SIZE});</li>
  <li>The number of script variables is higher than the maximum allowed ({@value #MAX_SCRIPT_VARS});</li>
  </ul>