module SimpleCov::Combine::LinesCombiner

def combine(coverage_a, coverage_b)
  coverage_a
    .zip(coverage_b)
    .map do |coverage_a_val, coverage_b_val|
      merge_line_coverage(coverage_a_val, coverage_b_val)
    end
end

def merge_line_coverage(first_val, second_val)
  sum = first_val.to_i + second_val.to_i
  if sum.zero? && (first_val.nil? || second_val.nil?)
    nil
  else
    sum
  end
end