How to use the pybuilder.utils.as_list function in pybuilder

def test_should_unwrap_single_list(self):
        self.assertEquals(["spam", "eggs"], as_list(["spam", "eggs"]))

def explicit_namespaces(self, value):
        self._explicit_namespaces = as_list(value)

for name in dir(project_module):
            candidate = getattr(project_module, name)
            name = normalize_candidate_name(candidate)

            description = getattr(candidate, DESCRIPTION_ATTRIBUTE, "")

            if getattr(candidate, TASK_ATTRIBUTE, None):
                dependencies = getattr(candidate, DEPENDS_ATTRIBUTE, None)

                task_dependencies = list()
                if dependencies:
                    dependencies = list(as_list(dependencies))
                    for d in dependencies:
                        if isinstance(d, optional):
                            d = as_list(d())
                            task_dependencies.extend([TaskDependency(item, True) for item in d])
                        else:
                            task_dependencies.append(TaskDependency(d))

                # Add injected
                if name in injected_task_dependencies:
                    task_dependencies.extend(injected_task_dependencies[name])
                    del injected_task_dependencies[name]

                self.logger.debug("Found task '%s' with dependencies %s", name, task_dependencies)
                self.execution_manager.register_task(
                    Task(name, candidate, task_dependencies, description))

            elif getattr(candidate, ACTION_ATTRIBUTE, None):
                before = getattr(candidate, BEFORE_ATTRIBUTE, None)
                after = getattr(candidate, AFTER_ATTRIBUTE, None)

description = getattr(candidate, DESCRIPTION_ATTRIBUTE) if hasattr(
                candidate, DESCRIPTION_ATTRIBUTE) else ""

            if hasattr(candidate, TASK_ATTRIBUTE) and getattr(candidate, TASK_ATTRIBUTE):
                dependencies = getattr(candidate, DEPENDS_ATTRIBUTE) if hasattr(candidate, DEPENDS_ATTRIBUTE) else None
                required_dependencies = []
                optional_dependencies = []

                # Add injected
                if name in task_dependencies:
                    injected_dependencies = task_dependencies[name]
                    required_dependencies.extend(injected_dependencies[0])
                    optional_dependencies.extend(injected_dependencies[1])

                if dependencies:
                    dependencies = list(as_list(dependencies))
                    for d in dependencies:
                        if type(d) is optional:
                            d = as_list(d())
                            optional_dependencies += d
                        else:
                            required_dependencies.append(d)
                self.logger.debug("Found task '%s' with required dependencies %s and optional dependencies %s", name,
                                  required_dependencies, optional_dependencies)
                self.execution_manager.register_task(
                    Task(name, candidate, required_dependencies, description, optional_dependencies))

            elif hasattr(candidate, ACTION_ATTRIBUTE) and getattr(candidate, ACTION_ATTRIBUTE):
                before = getattr(candidate, BEFORE_ATTRIBUTE) if hasattr(
                    candidate, BEFORE_ATTRIBUTE) else None
                after = getattr(candidate, AFTER_ATTRIBUTE) if hasattr(
                    candidate, AFTER_ATTRIBUTE) else None

add_task_dependency(d, name, True)
                        else:
                            add_task_dependency(d, name, False)

        for name in dir(project_module):
            candidate = getattr(project_module, name)
            name = normalize_candidate_name(candidate)

            description = getattr(candidate, DESCRIPTION_ATTRIBUTE, "")

            if getattr(candidate, TASK_ATTRIBUTE, None):
                dependencies = getattr(candidate, DEPENDS_ATTRIBUTE, None)

                task_dependencies = list()
                if dependencies:
                    dependencies = list(as_list(dependencies))
                    for d in dependencies:
                        if isinstance(d, optional):
                            d = as_list(d())
                            task_dependencies.extend([TaskDependency(item, True) for item in d])
                        else:
                            task_dependencies.append(TaskDependency(d))

                # Add injected
                if name in injected_task_dependencies:
                    task_dependencies.extend(injected_task_dependencies[name])
                    del injected_task_dependencies[name]

                self.logger.debug("Found task '%s' with dependencies %s", name, task_dependencies)
                self.execution_manager.register_task(
                    Task(name, candidate, task_dependencies, description))

def _prepare_tasks(self, tasks):
        if not len(tasks):
            if self.project.default_task:
                tasks += as_list(self.project.default_task)
            else:
                raise PyBuilderException("No default task given.")
        else:
            new_tasks = [task for task in tasks if task[0] not in ("+", "^") or task in ("+", "^")]
            append_tasks = [task[1:] for task in tasks if task[0] == "+" and task != "+"]
            remove_tasks = [task[1:] for task in tasks if task[0] == "^" and task != "^"]

            if len(new_tasks):
                del tasks[:]
                tasks.extend(new_tasks)
                tasks.extend(append_tasks)
                for task in remove_tasks:
                    try:
                        tasks.remove(task)
                    except ValueError:
                        pass

def build_pip_install_options(index_url=None, extra_index_url=None, upgrade=False, insecure_installs=None,
                              force_reinstall=False, target_dir=None, verbose=False, trusted_host=None,
                              constraint_file=None, eager_upgrade=False):
    options = []
    if index_url:
        options.append("--index-url")
        options.append(index_url)

    if extra_index_url:
        extra_index_urls = as_list(extra_index_url)
        for url in extra_index_urls:
            options.append("--extra-index-url")
            options.append(url)

    if trusted_host:
        trusted_hosts = as_list(trusted_host)
        for host in trusted_hosts:
            options.append("--trusted-host")
            options.append(host)

    if upgrade:
        options.append("--upgrade")
        if pip_common.pip_version >= "9.0":
            options.append("--upgrade-strategy")
            if eager_upgrade:
                options.append("eager")

def as_pip_install_target(mixed):
    arguments = []
    targets = as_list(mixed)

    for target in targets:
        if isinstance(target, RequirementsFile):
            arguments.extend(("-r", target.name))
        elif isinstance(target, Dependency):
            if target.url:
                arguments.append(target.url)
            else:
                arguments.append("{0}{1}".format(target.name, build_dependency_version_string(target)))
        else:
            arguments.append(str(target))

    return arguments

for name in as_list(names):
                if not isinstance(name, basestring):
                    name = normalize_candidate_name(name)
                if name not in task_dependencies:
                    task_dependencies[name] = (list(), list())
                task_dependencies[name][1 if optional else 0].append(depends_on)

        for name in dir(project_module):
            candidate = getattr(project_module, name)
            name = normalize_candidate_name(candidate)

            if hasattr(candidate, TASK_ATTRIBUTE) and getattr(candidate, TASK_ATTRIBUTE):
                dependents = getattr(candidate, DEPENDENTS_ATTRIBUTE) if hasattr(candidate,
                                                                                 DEPENDENTS_ATTRIBUTE) else None
                if dependents:
                    dependents = list(as_list(dependents))
                    for d in dependents:
                        if type(d) is optional:
                            d = d()
                            add_task_dependency(d, candidate, True)
                        else:
                            add_task_dependency(d, candidate, False)

        for name in dir(project_module):
            candidate = getattr(project_module, name)
            name = normalize_candidate_name(candidate)

            description = getattr(candidate, DESCRIPTION_ATTRIBUTE) if hasattr(
                candidate, DESCRIPTION_ATTRIBUTE) else ""

            if hasattr(candidate, TASK_ATTRIBUTE) and getattr(candidate, TASK_ATTRIBUTE):
                dependencies = getattr(candidate, DEPENDS_ATTRIBUTE) if hasattr(candidate, DEPENDS_ATTRIBUTE) else None