code: func (c *Client) OAuthTokenCreate(grant OAuthTokenCreateGrant, client OAuthTokenCreateClient, refreshToken OAuthTokenCreateRefreshToken) (*OAuthToken, error) {
  	params := struct {
  		Grant        OAuthTokenCreateGrant        `json:"grant"`
  		Client       OAuthTokenCreateClient       `json:"client"`
  		RefreshToken OAuthTokenCreateRefreshToken `json:"refresh_token"`
  	}{
  		Grant:        grant,
  		Client:       client,
  		RefreshToken: refreshToken,
  	}
  	var oauthTokenRes OAuthToken
  	return &oauthTokenRes, c.Post(&oauthTokenRes, "/oauth/tokens", params)
  }
docs: // Create a new OAuth token.
  //
  // grant is the grant used on the underlying authorization. client is the OAuth
  // client secret used to obtain token. refreshToken is the refresh token for
  // this authorization.