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difference between each.with_index and each_with_index in Ruby?

I'm really confused about the difference between each.with_index and each_with_index. They have different types but seem to be identical in practice.

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The with_index method takes an optional parameter to offset the starting index. each_with_index does the same thing, but has no optional starting index.

For example:

[:foo, :bar, :baz].each.with_index(2) do |value, index|
    puts "#{index}: #{value}"
end

[:foo, :bar, :baz].each_with_index do |value, index|
    puts "#{index}: #{value}"
end

Outputs:

2: foo
3: bar
4: baz

0: foo
1: bar
2: baz

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