Imports a stdlib path and returns a handle to it
        eg. self._import("typing", "Optional") -> "Optional"

def _import(self, path, name):
        # type: (Text, Text) -> Text
        """Imports a stdlib path and returns a handle to it
        eg. self._import("typing", "Optional") -> "Optional"
        """
        imp = path.replace('/', '.')
        self.imports[imp].add(name)
        return name