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select 

        # Hash.select

(from ruby core)
---
    hash.select {|key, value| ... } -> new_hash
    hash.select -> new_enumerator

---

Hash#filter is an alias for Hash#select.

Returns a new Hash object whose entries are those for which the block
returns a truthy value:
    h = {foo: 0, bar: 1, baz: 2}
    h.select {|key, value| value < 2 } # => {:foo=>0, :bar=>1}

Returns a new Enumerator if no block given:
    h = {foo: 0, bar: 1, baz: 2}
    e = h.select # => #<Enumerator: {:foo=>0, :bar=>1, :baz=>2}:select>
    e.each {|key, value| value < 2 } # => {:foo=>0, :bar=>1}

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