Python:ValueError:too Many values to unpack

EG1:

>>>a,b= (a)

Traceback (most recent):

File "<stdin>", line 1,in <module>

Valueerror:too Many values to unpack (expected 2)

Error reason: When a tuple value is assigned to a tuple variable, the number of variables is not sufficient

Can be changed to a,b,c= (+/-) or other variables

EG2:

>>>import Collections

>>>s=[(' y ', 1), (' B ', 1), (' R '), (' Y ', 2)]

>>>d=collections.defaultdict (list)

>>>for K,v in S:

..... d[k].append (v)

...

Traceback (most recent):

File "<stdin>", line 1,in <module>

Valueerror:too Many values to unpack (expected 2)

Cause of Error: s=[(' y ', 1), (' B ', 1), (' R '), (' Y ', 2)] The number of variables (' R ') is not enough

Can be changed to s=[(' Y ', 1), (' B ', 1), (' R ', 1), (' Y ', 2)] or other values can be

Python:ValueError:too Many values to unpack