use literal dictionary for performance speedup. code review comment.

rho/scancommand.py

@@ -49,7 +49,7 @@ def _create_ping_inventory(vault, vault_pass, profile_ranges, profile_port,
     success_map = defaultdict(list)
     best_map = defaultdict(list)
     mapped_hosts = set()
-    hosts_dict = dict()
+    hosts_dict = {}
 
     for profile_range in profile_ranges:
         # pylint: disable=anomalous-backslash-in-string
@@ -62,7 +62,7 @@ def _create_ping_inventory(vault, vault_pass, profile_ranges, profile_port,
         else:
             hosts_dict[hostname] = None
 
-    vars_dict = dict()
+    vars_dict = {}
     for cred_item in profile_auth_list:
         cred_pass = cred_item.get('password')
         cred_sshkey = cred_item.get('ssh_key_file')
@@ -156,10 +156,10 @@ def _create_hosts_auths_file(success_map, profile):
 # pylint: disable=too-many-locals
 def _create_main_inventory(vault, success_hosts, success_port_map, best_map,
                            profile):
-    yml_dict = dict()
+    yml_dict = {}
 
     # Create section of successfully connected hosts
-    alpha_hosts = dict()
+    alpha_hosts = {}
     for host in success_hosts:
         ascii_host = str_to_ascii(host)
         ascii_port = str_to_ascii(str(success_port_map[host]))