slack: Lookup dir_name key in dict instead of in dict_keys.
slack: Lookup dir_name key in dict instead of in dict_keys.

No reason to do the lookup in O(n) when we can do
it in average O(1) time complexity.

punchagan/zulip,eeshangarg/zulip,zulip/zulip,zulip/zulip,andersk/zulip,shubhamdhama/zulip,zulip/zulip,synicalsyntax/zulip,zulip/zulip,hackerkid/zulip,punchagan/zulip,andersk/zulip,shubhamdhama/zulip,hackerkid/zulip,eeshangarg/zulip,shubhamdhama/zulip,showell/zulip,brainwane/zulip,kou/zulip,showell/zulip,synicalsyntax/zulip,timabbott/zulip,kou/zulip,showell/zulip,hackerkid/zulip,hackerkid/zulip,punchagan/zulip,brainwane/zulip,synicalsyntax/zulip,eeshangarg/zulip,kou/zulip,synicalsyntax/zulip,andersk/zulip,zulip/zulip,rht/zulip,zulip/zulip,hackerkid/zulip,synicalsyntax/zulip,rht/zulip,eeshangarg/zulip,synicalsyntax/zulip,brainwane/zulip,kou/zulip,brainwane/zulip,shubhamdhama/zulip,andersk/zulip,brainwane/zulip,rht/zulip,shubhamdhama/zulip,rht/zulip,rht/zulip,timabbott/zulip,eeshangarg/zulip,rht/zulip,showell/zulip,andersk/zulip,showell/zulip,punchagan/zulip,shubhamdhama/zulip,rht/zulip,punchagan/zulip,synicalsyntax/zulip,zulip/zulip,kou/zulip,timabbott/zulip,showell/zulip,brainwane/zulip,timabbott/zulip,hackerkid/zulip,kou/zulip,timabbott/zulip,shubhamdhama/zulip,hackerkid/zulip,showell/zulip,timabbott/zulip,timabbott/zulip,kou/zulip,brainwane/zulip,punchagan/zulip,andersk/zulip,punchagan/zulip,eeshangarg/zulip,andersk/zulip,eeshangarg/zulip