old_contents: from .abc import AbstractAuthorizationPolicy, AbstractIdentityPolicy
  from .api import (authorized_userid, forget, has_permission, is_anonymous,
                    login_required, permits, remember, setup)
  from .cookies_identity import CookiesIdentityPolicy
  from .session_identity import SessionIdentityPolicy
  
  __version__ = '0.2.0'
  
  
  __all__ = ('AbstractIdentityPolicy', 'AbstractAuthorizationPolicy',
             'CookiesIdentityPolicy', 'SessionIdentityPolicy',
             'remember', 'forget', 'authorized_userid',
             'permits', 'setup', 'is_anonymous',
             'login_required', 'has_permission')
  
new_contents: from .abc import AbstractAuthorizationPolicy, AbstractIdentityPolicy
  from .api import (authorized_userid, forget, has_permission, is_anonymous,
                    login_required, permits, remember, setup)
  from .cookies_identity import CookiesIdentityPolicy
  from .session_identity import SessionIdentityPolicy
  from .jwt_identity import JWTIdentityPolicy
  
  __version__ = '0.2.0'
  
  
  __all__ = ('AbstractIdentityPolicy', 'AbstractAuthorizationPolicy',
             'CookiesIdentityPolicy', 'SessionIdentityPolicy',
             'JWTIdentityPolicy',
             'remember', 'forget', 'authorized_userid',
             'permits', 'setup', 'is_anonymous',
             'login_required', 'has_permission')
  
subject: add JWTIdentityPolicy into __init__ file. (#157)