whole_func_string: function (command, parameters, callback) {
        if (typeof parameters === 'function') {
          callback = parameters;
          parameters = {};
        }
  
        parameters || (parameters = {});
        parameters.command = command;
        parameters.nonce = nonce();
  
        const options = {
          method: 'POST',
          url: PRIVATE_API_URL,
          form: parameters,
          headers: this._getPrivateHeaders(parameters)
        };
  
        return this._request(options, callback);
      }
func_code_string: function (command, parameters, callback) {
        if (typeof parameters === 'function') {
          callback = parameters;
          parameters = {};
        }
  
        parameters || (parameters = {});
        parameters.command = command;
        parameters.nonce = nonce();
  
        const options = {
          method: 'POST',
          url: PRIVATE_API_URL,
          form: parameters,
          headers: this._getPrivateHeaders(parameters)
        };
  
        return this._request(options, callback);
      }
func_documentation_string: Make a private API request