### Question:
ValueScope extends Scope<NamedValue> { public DataValue value(String name) throws AmbiguousNameException { Ensure.not_null(name, "name == null"); NamedValue nv = find(name); if (nv == null) { return null; } return nv.value(); } ValueScope(TypeScope types); TypeScope typed_scope(); DataType type(String name); DataValue value(String name);  }### Answer:
@Test public void create_assign_obtain_values() throws Exception { m_vs.add(new NamedValue("a", m_ps.ascii().make("bar"))); DataValue vl = m_vs.value("a"); assertTrue(vl instanceof AsciiValue); AsciiValue sv = (AsciiValue) vl; assertEquals("bar", sv.value()); }
@Test public void obtain_non_existing_value() throws Exception { assertNull(m_vs.value("h")); }