### Question:
ClientFunction extends ClientOperator<ClientFunction> { public ClientFunction addArgument(ClientExpression expr) { this.operands.add(expr); return this; } ClientFunction();  ClientFunction(String functionName, List<ClientExpression> operands);  ClientFunction(ClientFunction source);  ClientFunction(String functionName); String getFunctionName(); ClientFunction setFunctionName(String functionName); ClientFunction addArgument(ClientExpression expr); @Override String toString(); @Override void accept(ClientELVisitor visitor); @Override boolean equals(Object o); @Override int hashCode(); @Override ClientFunction deepClone(); int getPrecedence(); static final String EXPRESSION_ID; }### Answer:
@Test public void addArgument() { ClientFunction instance = createFullyConfiguredInstance(); instance.addArgument(TEST_CLIENT_EXPRESSION); assertEquals(TEST_CLIENT_EXPRESSIONS, instance.getOperands()); }