Improve section spacing

Author: rhettinger

Doc/library/itertools.rst

@@ -847,6 +847,7 @@ and :term:`generators <generator>` which incur interpreter overhead.
    from math import comb, isqrt, prod, sumprod
    from operator import getitem, is_not, itemgetter, mul, neg, truediv
 
+
    # ==== Basic one liners ====
 
    def take(n, iterable):
@@ -918,6 +919,7 @@ and :term:`generators <generator>` which incur interpreter overhead.
        # all_equal('4٤௪౪໔', key=int) → True
        return len(take(2, groupby(iterable, key))) <= 1
 
+
    # ==== Data pipelines ====
 
    def unique_justseen(iterable, key=None):
@@ -1026,6 +1028,7 @@ and :term:`generators <generator>` which incur interpreter overhead.
            while True:
                yield function()
 
+
    # ==== Mathematical operations ====
 
    def multinomial(*counts):
@@ -1045,6 +1048,7 @@ and :term:`generators <generator>` which incur interpreter overhead.
        # sum_of_squares([10, 20, 30]) → 1400
        return sumprod(*tee(iterable))
 
+
    # ==== Matrix operations ====
 
    def reshape(matrix, columns):
@@ -1063,6 +1067,7 @@ and :term:`generators <generator>` which incur interpreter overhead.
        n = len(m2[0])
        return batched(starmap(sumprod, product(m1, transpose(m2))), n)
 
+
    # ==== Polynomial arithmetic ====
 
    def convolve(signal, kernel):
@@ -1119,6 +1124,7 @@ and :term:`generators <generator>` which incur interpreter overhead.
        powers = reversed(range(1, n))
        return list(map(mul, coefficients, powers))
 
+
    # ==== Number theory ====
 
    def sieve(n):