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# File 'lib/ru/stream.rb', line 2
def [](number_or_range, length=1)
if number_or_range.kind_of? Range
range = number_or_range
if range.begin < 0 || range.end < -1 || (range.exclude_end? && range.end == -1)
raise ArgumentError, "Stream doesn't support negative indexes, except x..-1"
end
if range.end == -1
drop(range.begin)
else
each_with_index.select { |_, index|
range.cover?(index)
}
end
else
number = number_or_range
if number >= 0
result = drop(number)
if length >= 0
result.take(length)
else
nil
end
else
raise ArgumentError, "Stream doesn't support negative indexes"
end
end
end
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