unpacking with star expressions

__author__ = 'Work'

'''
Star unpacking is similar to list processing features of other functional languages. Lists can be split into head and
tails components.
'''

items = [1, 10, 7, 4, 5, 9]
head, *tail = items

# Functions can use head and tail splitting to carry out some recursive algorithm.
# Ex:
def summation(items):
    head, *tail = items
    return head + summation(tail) if tail else head

items = [2923,239,21,3,5,-12,239,-1233]

x = sum(items)
y = summation(items)
print('BIF sum(): ',x, '\n', "summation(): ", y, '\n', 'x == y ? ', x == y)
# If items greater than 1 return the sum of all tail elements and the head. If not return just the head
# (cannot unpack 0 values).