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sum_with_block

➕ Conditional Summation Using sum​

The sum method accepts an initial accumulator and a block, letting you compute custom totals in one pass. Replace map+reduce combos with sum and inline logic for brevity and clarity.

numbers = [1, 2, 3, 4, 5]
# Sum only even numbers doubled
result = numbers.sum(0) do |n|
  n.even? ? n * 2 : 0
end
# => 12   # (2*2 + 4*2)