def METHOD_NAME(self):
    pip_args = ['install', '-v', 'wheel', 'pip>=8']
    env = dict(os.environ)
    env.update(self.build_env_vars)
    self._run_pip(pip_args, env=env)
    pip_calls = []
    pip_args = []
    for key, val in {**self._requirements,
                     **self._base_requirements}.items():
        if key.startswith("pip+"):
            if val:
                pip_args.append((key[4:], val))
            else:
                pip_args.append((key[4:], None))
    for pkgname, pipval in pip_args:
        pip_calls.append(util.construct_pip_call(self._run_pip, pkgname, pipval))
    for pipcall in pip_calls:
        pipcall()