Overhaul the argument parsing API

lib/argparse/Args.dart

@@ -3,7 +3,6 @@ import 'package:libac_dart/argparse/types/Integers.dart';
 import 'package:libac_dart/argparse/types/String.dart';
 
 abstract class Argument<T> {
-  bool hasValue = false;
   String name;
 
   String description;
@@ -46,53 +45,75 @@ abstract class Argument<T> {
   }
 
   ArgumentType getType();
+
+  bool hasValue();
 }
 
 enum ArgumentType { STRING, BOOL, INTEGER, DOUBLE }
 
 class Arguments {
-  Map<String, Argument> _args = {};
+  Map<String, Argument> args = {};
 
   void setArg(Argument arg) {
-    _args[arg.name] = arg;
+    args[arg.name] = arg;
   }
 
-  int get count => _args.length;
+  int get count => args.length;
 
   List<String> getArgNames() {
-    List<String> args = [];
-    for (MapEntry<String, Argument> entry in _args.entries) {
-      args.add(entry.key);
+    List<String> argsx = [];
+    for (MapEntry<String, Argument> entry in args.entries) {
+      argsx.add(entry.key);
     }
 
-    return args;
+    return argsx;
+  }
+
+  /// Removes the argument if present. Otherwise does nothing.
+  ///
+  /// Returns true if the argument was present and removed. False otherwise.
+  bool removeArg(String name) {
+    if (args.containsKey(name)) {
+      args.remove(name);
+      return true;
+    } else
+      return false;
   }
 
   Argument? getArg(String name) {
     if (hasArg(name))
-      return _args[name];
+      return args[name];
     else
       return null;
   }
 
   bool hasArg(String name) {
-    return _args.containsKey(name);
+    return args.containsKey(name);
   }
 
   bool argHasValue(String name) {
     if (hasArg(name)) {
       Argument arg = getArg(name)!;
-      return arg.hasValue;
+      return arg.hasValue();
     } else
       throw new Exception("Warning: No such argument");
   }
 
   Arguments clone() {
-    Arguments args = Arguments();
-    for (MapEntry<String, Argument> entry in _args.entries) {
-      args.setArg(entry.value.clone());
+    Arguments argsx = Arguments();
+    for (MapEntry<String, Argument> entry in args.entries) {
+      argsx.setArg(entry.value.clone());
     }
 
-    return args;
+    return argsx;
+  }
+
+  List<Argument> getArgumentsList() {
+    List<Argument> argsx = [];
+    for (var entry in args.entries) {
+      argsx.add(entry.value);
+    }
+
+    return argsx;
   }
 }