Spider urllib3 trasport requires pycurl

[MaximKiselev]

Traceback (most recent call last):
  File "*", line 2, in <module>
    from grab.spider import Spider, Task
  File "*\py36\lib\site-packages\grab\spider\__init__.py", line 1, in <module>
    from grab.spider.base import Spider  # noqa
  File "*\py36\lib\site-packages\grab\spider\base.py", line 22, in <module>
    from grab.spider.transport.multicurl import MulticurlTransport
  File "*\py36\lib\site-packages\grab\spider\transport\multicurl.py", line 1, in <module>
    import pycurl
ModuleNotFoundError: No module named 'pycurl'

How to reproduce?

1. uninstall pycurl

from grab.spider import Spider, Task