diff --git a/tools/icu/icutrim.py b/tools/icu/icutrim.py
index a825b18ac0c8c3..25bd99d9cb260d 100755
--- a/tools/icu/icutrim.py
+++ b/tools/icu/icutrim.py
@@ -163,17 +163,15 @@ def runcmd(tool, cmd, doContinue=False):
 config=json.load(fi)
 fi.close()
 
-if (options.locales):
-  if not config.has_key("variables"):
-    config["variables"] = {}
-  if not config["variables"].has_key("locales"):
-    config["variables"]["locales"] = {}
-  config["variables"]["locales"]["only"] = options.locales.split(',')
-
-if (options.verbose > 6):
+if options.locales:
+    config["variables"] = config.get("variables", {})
+    config["variables"]["locales"] = config["variables"].get("locales", {})
+    config["variables"]["locales"]["only"] = options.locales.split(',')
+
+if options.verbose > 6:
     print(config)
 
-if(config.has_key("comment")):
+if "comment" in config:
     print("%s: %s" % (options.filterfile, config["comment"]))
 
 ## STEP 1 - copy the data file, swapping endianness
@@ -186,53 +184,47 @@ def runcmd(tool, cmd, doContinue=False):
 listfile = os.path.join(options.tmpdir,"icudata.lst")
 runcmd("icupkg", "-l %s > %s""" % (outfile, listfile))
 
-fi = open(listfile, 'rb')
-items = fi.readlines()
-items = [items[i].strip() for i in range(len(items))]
-fi.close()
-
+with open(listfile, 'rb') as fi:
+    items = [line.strip() for line in fi.read().decode("utf-8").splitlines()]
 itemset = set(items)
 
-if (options.verbose>1):
-    print("input file: %d items" % (len(items)))
+if options.verbose > 1:
+    print("input file: %d items" % len(items))
 
 # list of all trees
 trees = {}
 RES_INDX = "res_index.res"
 remove = None
 # remove - always remove these
-if config.has_key("remove"):
+if "remove" in config:
     remove = set(config["remove"])
 else:
     remove = set()
 
 # keep - always keep these
-if config.has_key("keep"):
+if "keep" in config:
     keep = set(config["keep"])
 else:
     keep = set()
 
 def queueForRemoval(tree):
     global remove
-    if not config.has_key("trees"):
-        # no config
-        return
-    if not config["trees"].has_key(tree):
+    if tree not in config.get("trees", {}):
         return
     mytree = trees[tree]
-    if(options.verbose>0):
+    if options.verbose > 0:
         print("* %s: %d items" % (tree, len(mytree["locs"])))
     # do varible substitution for this tree here
     if isinstance(config["trees"][tree], basestring):
         treeStr = config["trees"][tree]
-        if(options.verbose>5):
+        if options.verbose > 5:
             print(" Substituting $%s for tree %s" % (treeStr, tree))
-        if(not config.has_key("variables") or not config["variables"].has_key(treeStr)):
+        if treeStr not in config.get("variables", {}):
             print(" ERROR: no variable:  variables.%s for tree %s" % (treeStr, tree))
             sys.exit(1)
         config["trees"][tree] = config["variables"][treeStr]
     myconfig = config["trees"][tree]
-    if(options.verbose>4):
+    if options.verbose > 4:
         print(" Config: %s" % (myconfig))
     # Process this tree
     if(len(myconfig)==0 or len(mytree["locs"])==0):
@@ -240,7 +232,7 @@ def queueForRemoval(tree):
             print(" No processing for %s - skipping" % (tree))
     else:
         only = None
-        if myconfig.has_key("only"):
+        if "only" in myconfig:
             only = set(myconfig["only"])
             if (len(only)==0) and (mytree["treeprefix"] != ""):
                 thePool = "%spool.res" % (mytree["treeprefix"])
@@ -297,7 +289,7 @@ def addTreeByType(tree, mytree):
         treeitems = fi.readlines()
         trees[tree]["locs"] = [treeitems[i].strip() for i in range(len(treeitems))]
         fi.close()
-        if(not config.has_key("trees") or not config["trees"].has_key(tree)):
+        if tree not in config.get("trees", {}):
             print(" Warning: filter file %s does not mention trees.%s - will be kept as-is" % (options.filterfile, tree))
         else:
             queueForRemoval(tree)
@@ -315,10 +307,8 @@ def removeList(count=0):
         oldcount = len(remove)
         hackerrfile=os.path.join(options.tmpdir, "REMOVE.err")
         removefile = os.path.join(options.tmpdir, "REMOVE.lst")
-        fi = open(removefile, 'wb')
-        for i in remove:
-            print(i, file=fi)
-        fi.close()
+        with open(removefile, 'wb') as fi:
+            fi.write('\n'.join(remove).encode("utf-8") + b'\n')
         rc = runcmd("icupkg","-r %s %s 2> %s" %  (removefile,outfile,hackerrfile),True)
         if rc != 0:
             if(options.verbose>5):
@@ -352,7 +342,7 @@ def removeList(count=0):
 # now, fixup res_index, one at a time
 for tree in trees:
     # skip trees that don't have res_index
-    if not trees[tree].has_key("hasIndex"):
+    if "hasIndex" not in trees[tree]:
         continue
     treebunddir = options.tmpdir
     if(trees[tree]["treeprefix"]):