'Set package_name
>>> docwriter = ApiDocWriter(\'sphinx\')
>>> import sphinx
>>> docwriter.root_path == sphinx.__path__[0]
True
>>> docwriter.package_name = \'docutils\'
>>> import docutils
>>> docwriter.root_path == docutils.__path__[0]
True'

def set_package_name(self, package_name):

    self._package_name = package_name
    self.root_module = __import__(package_name)
    self.root_path = self.root_module.__path__[0]
    self.written_modules = None
