keys - Return array of keys in a dictionarySynopsis:
dict keys -> array
<> keys -> [/key1 ... /keyn]
<< /a 1 /b 2>> keys -> [/a /b]
"keys" converts the keys in a given dictionary to an array.
The order of elements is the same as for the "values" command.
dict is a dictionary which may be empty
no errors are issued.
The commands "keys" and "values" return the same order of
elements, when applied to the same dictionary. Apart from that,
there is no particular order of elements in the returned array.
First Version: 27-jun-2008