array:get_keys

Return all the keys of the given array.

array:get_keys(ARRAY $array) : ARRAY

array:get_keys(["hello","world"])
#=> [ 0, 1 ]

array:get_keys(["name"=>"SunSed", "version"=> "inf"])
#=> [ "name", "version" ]

array:get_keys([])
#=> []

# note: since, no array keys are always unique, the returned array has no duplicates.