#!/usr/bin/env python
import matplotlib
import sys
print(sys.version)
print(matplotlib.__version__)
import matplotlib.pyplot as plt

plt.figure()
a = plt.annotate(s="test", xy=(0.5, 0.5))
print(a)

/home/jneal/miniconda3/envs/py36/bin/python /home/jneal/Phd/Codes/annotatetest.py
3.6.4 |Anaconda, Inc.| (default, Jan 16 2018, 18:10:19) 
[GCC 7.2.0]
2.2.3
Annotation(0.5,0.5,'test')

Process finished with exit code 0

3.6.4 |Anaconda, Inc.| (default, Jan 16 2018, 18:10:19) 
[GCC 7.2.0]
3.0.0
Traceback (most recent call last):
  File "annotatetest.py", line 10, in <module>
    a = plt.annotate(s="test", xy=(0.5, 0.5))
TypeError: annotate() missing 1 required positional argument: 'text'