comma operator
tuples - How does Python's comma operator works during assignment? - Stack Overflow
https://stackoverflow.com/questions/11502268/how-does-pythons-comma-operator-works-during-assignment
MetPy Mondays
`#118 - Legends and Subplots : Unidata Developer's Blog
https://www.unidata.ucar.edu/blogs/developer/entry/metpy-mondays-118-legends-and
code:python
x=
5
a,=x
print(a)
5