Proposal for a new array function

On the proposal for a new function to array that could be called
has_numeric_keys I believe would be the most appropriate as the name of the
function as well as its functionality. I believe that the creation of a
typo checking function would be more interesting. In other languages array
contains only numerical keys while hash have arbitrary keys. So creating a
function is_hash as would be the case.

Sample:

$arr = [1, 2, 3];

is_hash (arr $) // -> false

$hash = [ '23' => 'FOO', 'baz' => 12 'bar' => 89];

is_hash ($ hash) // -> true