code: func (s *TeamsService) GetTeamMembership(ctx context.Context, team int64, user string) (*Membership, *Response, error) {
  	u := fmt.Sprintf("teams/%v/memberships/%v", team, user)
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	req.Header.Set("Accept", mediaTypeNestedTeamsPreview)
  
  	t := new(Membership)
  	resp, err := s.client.Do(ctx, req, t)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return t, resp, nil
  }
docs: // GetTeamMembership returns the membership status for a user in a team.
  //
  // GitHub API docs: https://developer.github.com/v3/teams/members/#get-team-membership