Could not fetch URL https://pypi.python.org/simple/xlrd/: There was a problem confirming the ssl certificate: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:661) - skipping
Could not find a version that satisfies the requirement xlrd (from versions: )
No matching distribution found for xlrd
解决方案：
$ curl https://bootstrap.pypa.io/get-pip.py >> get-pip.py
$ python get-pip.py
然后重新pip install 模块名
在安装
pip3 install watchdog nose
