Inject an attribute in a class from it's class frame.
    Use in class annnotation to create methods/properties dynamically
    at class creation time without dealing with metaclass.

    depth parameter specify the stack depth from the class definition.

def injectAttribute(annotationName, depth, attr, value):
    """
    Inject an attribute in a class from it's class frame.
    Use in class annnotation to create methods/properties dynamically
    at class creation time without dealing with metaclass.

    depth parameter specify the stack depth from the class definition.
    """
    locals = reflect.class_locals(depth, annotationName)
    injections = locals.get(_ATTRIBUTE_INJECTIONS_ATTR, None)
    if injections is None:
        injections = list()
        locals[_ATTRIBUTE_INJECTIONS_ATTR] = injections
    injections.append((attr, value))