Meaning of using commas and underscores with Python assignment operator?
d2, = values[s] is just like a,b=f(), except for unpacking 1 element tuples.
>>> T=(1,)>>> a=T>>> a(1,)>>> b,=T>>> b1>>> a is tuple, b is an integer.
_ is like any other variable name but usually it means "I don't care about this variable".
The second question: it is "value unpacking". When a function returns a tuple, you can unpack its elements.
>>> x=("v1", "v2")>>> a,b = x>>> print a,bv1 v2
The _ in the Python shell also refers to the value of the last operation. Hence
>>> 11>>> _1The commas refer to tuple unpacking. What happens is that the return value is a tuple, and so it is unpacked into the variables separated by commas, in the order of the tuple's elements.