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v = m.get(k);m.getOrDefault(k, null);v, ok := m[k]ok is set to true if m has an entry for the key k, false otherwise.
v := m[k]If m doesn't have the key k, then v is set to the zero value of m's values type.
var v = m[k];If no entry, throw an exception; use TryGetValue or GetValueOrDefault instead.
v = m.get(k);If k does not exist in m, v will be `undefined`.
local v=m[k]v will be nil if there's no index k in m.
$v = $m{$k};Returns undef when the hash lookup fails
$v = $m{$k} // 'foobar';defined-or operator, to assign a default value when the lookup fails
v = m[k]When the key k is not found, v will be determined by the hashes default proc (if any) or its default value nil.