human
5. Default and keyword arguments
5.1 Write a function that computes the sum of a list with an optional starting value. If no starting value is provided, it should sum from 0.

Can you provide a the Python code you requested?
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#Here is the Python code you requested.
# TODO def sum_list...

assert(sum_list([1, 2, 3]) == 6)
assert(sum_list([1, 2, 3], 5) == 11)