code: public function setConfig($name, $value)
      {
          if ($name == self::PARAM_FORM || $name == self::PARAM_MULTIPART) {
              return $this;
          }
  
          if ($name == 'headers' || $name == self::PARAM_FORM || $name == self::PARAM_MULTIPART) {
              if (is_array($value)) {
                  $obj = $name == 'headers'
                      ? $this->withHeaders($value)
                      : $this->withParams($value, $name);
                  $this->configs = $obj->configs;
                  $this->client  = $obj->client;
                  $this->request = $obj->request;
              }
  
              return $this;
          }
  
          $this->configs[$name] = $value;
          return $this->buildConfigClient();
      }
docs: Set Config
  
  @param mixed $name
  @param mixed $value
  @return static