This is a followup to #26616 which changed error message for this case:

bar := bufio.NewReader(...)
line := bar.ReadString()

from multiple-value bar.ReadString() in single-value context to 1 variable but 2 values.

In Python, if function returns multiple arguments (a tuple), it is completely okay to assign it to one variable:

>>> def xxx():
...   return 1,2
... 
>>> a = xxx()
>>> b, c = xxx()
>>> a
(1, 2)
>>> b
1
>>> c
2

Therefore if a Python coder like me is reading the Go code, it is not completely obvious what is going on, which was the reason to fill #26616. The error message that fixes #26616 is good, but could be improved to include return values for explicit context that the error cause is in return type of the function and not in the assignment statement.