code: func (m *MembershipsClient) Create(ctx context.Context, userID, orgID, teamID *identity.ID) error {
  	if orgID == nil {
  		return errors.New("invalid org")
  	}
  	if userID == nil {
  		return errors.New("invalid user")
  	}
  	if teamID == nil {
  		return errors.New("invalid team")
  	}
  
  	membershipBody := primitive.Membership{
  		OwnerID: userID,
  		OrgID:   orgID,
  		TeamID:  teamID,
  	}
  
  	ID, err := identity.NewMutable(&membershipBody)
  	if err != nil {
  		return err
  	}
  
  	membership := envelope.Membership{
  		ID:      &ID,
  		Version: 1,
  		Body:    &membershipBody,
  	}
  
  	return m.client.RoundTrip(ctx, "POST", "/memberships", nil, &membership, nil)
  }
docs: // Create requests addition of a user to a team