public void undefinedExpr(boolean is_defined) {
    CompiledValue value = pop();
    push(new CompiledUndefined(value, is_defined));
  }
Processes import statements only. This compiler instance remembers the imports and can be used
to compile other strings with this context info
geode-core/src/main/java/org/apache/geode/cache/query/internal/QCompiler.java