add fp2 sample
This commit is contained in:
Oli Sturm
@@ -0,0 +1,46 @@
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using CsharpFp2.Domain;
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using CsharpFp2.Infrastructure;
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namespace CsharpFp2.Application;
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// delegate type is optional, but nice to illustrate
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public delegate WithdrawResult WithdrawMoney(Guid accountId, decimal amount);
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public static class AccountApplication
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{
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public static WithdrawMoney CreateWithdrawMoney(
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LoadAccount loadAccount,
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SaveAccount saveAccount
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)
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{
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return (accountId, amount) =>
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{
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var account =
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loadAccount(accountId) ?? throw new InvalidOperationException("Account not found.");
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Console.WriteLine(
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$"[App] Account loaded. Current balance: {account.Balance.Amount:0.00}"
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);
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Console.WriteLine($"[App] Executing withdrawal of {amount:0.00}...");
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switch (AccountDomain.Withdraw(account, new Money(amount)))
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{
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case WithdrawResult.Success s:
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{
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Console.WriteLine(
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$"[App] Withdrawal applied. New balance: {s.Account.Balance.Amount:0.00}"
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);
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saveAccount(s.Account);
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Console.WriteLine("[App] Account persisted.");
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return s;
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}
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case var other:
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{
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Console.Error.WriteLine($"[App Error] Withdrawal failed. Error: {other}");
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return other;
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}
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}
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};
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}
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}
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@@ -0,0 +1,42 @@
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namespace CsharpFp2.Domain;
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public sealed record Account(Guid Id, Money Balance);
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public abstract record WithdrawResult
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{
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public sealed record Success(Account Account) : WithdrawResult;
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public sealed record AmountMustBePositive : WithdrawResult;
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public sealed record InsufficientBalance(Money balance, Money amount) : WithdrawResult;
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}
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public static class AccountDomain
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{
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public static Account Open(Guid id, Money openingBalance)
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{
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// Assuming we don't intend to allow invalid open balances to be passed
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// here, we can view this as a technical (i.e. dev-time) error and
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// stick to an exception.
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if (openingBalance.Amount < 0)
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throw new ArgumentOutOfRangeException(nameof(openingBalance));
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return new Account(id, openingBalance);
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}
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public static WithdrawResult Withdraw(Account account, Money amount)
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{
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if (amount.Amount <= 0)
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return new WithdrawResult.AmountMustBePositive();
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if (account.Balance.Amount < amount.Amount)
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return new WithdrawResult.InsufficientBalance(account.Balance, amount);
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return new WithdrawResult.Success(
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account with
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{
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Balance = account.Balance.Subtract(amount),
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}
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);
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}
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}
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@@ -0,0 +1,8 @@
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namespace CsharpFp2.Domain;
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public sealed record Money(decimal Amount)
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{
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public Money Add(Money other) => new(Amount + other.Amount);
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public Money Subtract(Money other) => new(Amount - other.Amount);
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}
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@@ -0,0 +1,41 @@
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using CsharpFp2.Domain;
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namespace CsharpFp2.Infrastructure;
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// If we don't like working with generic delegates directly, we can
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// create custom named delegate types.
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public delegate Account? LoadAccount(Guid id);
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public delegate void SaveAccount(Account accunt);
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// If we don't want to use tuples, or you really miss the idea of a combined "interface",
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// we can create a named container
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// public sealed record AccountPersistence(LoadAccount Load, SaveAccount Save);
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public static class InMemoryAccount
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{
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public static (LoadAccount, SaveAccount) Create()
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{
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Dictionary<Guid, Account> store = new();
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Account? GetById(Guid id)
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{
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var found = store.TryGetValue(id, out var account);
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Console.WriteLine(
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found ? $"[Repo] Loaded account {id}" : $"[Repo] Account {id} not found"
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);
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return found ? account : null;
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}
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void Save(Account account)
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{
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store[account.Id] = account;
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Console.WriteLine(
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$"[Repo] Saved account {account.Id} with balance {account.Balance.Amount:0.00}"
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);
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}
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return (GetById, Save);
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}
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}
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@@ -0,0 +1,18 @@
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using CsharpFp2.Application;
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using CsharpFp2.Domain;
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using CsharpFp2.Infrastructure;
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Console.WriteLine("[csharp-fp2] Starting withdraw money demo...");
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var (loadAccount, saveAccount) = InMemoryAccount.Create();
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var withdrawMoney = AccountApplication.CreateWithdrawMoney(loadAccount, saveAccount);
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var accountId = Guid.NewGuid();
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Console.WriteLine($"[csharp-fp2] Seeding account {accountId} with opening balance 200.00");
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saveAccount(new Account(accountId, new Money(200m)));
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decimal amount = 100m;
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Console.WriteLine($"[csharp-fp2] Executing withdrawal {amount:0.00} from account {accountId}");
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withdrawMoney(accountId, amount);
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Console.WriteLine("[csharp-fp2] Demo completed.");
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@@ -0,0 +1,9 @@
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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net10.0</TargetFramework>
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<RootNamespace>CsharpFp2</RootNamespace>
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<ImplicitUsings>enable</ImplicitUsings>
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<Nullable>enable</Nullable>
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</PropertyGroup>
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</Project>
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+15
@@ -17,6 +17,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp-oop-simplified2", "c
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EndProject
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Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp-fp1", "csharp-fp1\csharp-fp1.csproj", "{C9D46510-994A-4C43-BA8F-33CA9BED79D0}"
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EndProject
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Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp-fp2", "csharp-fp2\csharp-fp2.csproj", "{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}"
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EndProject
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Global
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GlobalSection(SolutionConfigurationPlatforms) = preSolution
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Debug|Any CPU = Debug|Any CPU
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@@ -87,6 +89,18 @@ Global
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{C9D46510-994A-4C43-BA8F-33CA9BED79D0}.Release|x64.Build.0 = Release|Any CPU
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{C9D46510-994A-4C43-BA8F-33CA9BED79D0}.Release|x86.ActiveCfg = Release|Any CPU
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{C9D46510-994A-4C43-BA8F-33CA9BED79D0}.Release|x86.Build.0 = Release|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Debug|Any CPU.Build.0 = Debug|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Debug|x64.ActiveCfg = Debug|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Debug|x64.Build.0 = Debug|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Debug|x86.ActiveCfg = Debug|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Debug|x86.Build.0 = Debug|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Release|Any CPU.ActiveCfg = Release|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Release|Any CPU.Build.0 = Release|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Release|x64.ActiveCfg = Release|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Release|x64.Build.0 = Release|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Release|x86.ActiveCfg = Release|Any CPU
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A}.Release|x86.Build.0 = Release|Any CPU
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EndGlobalSection
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GlobalSection(SolutionProperties) = preSolution
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HideSolutionNode = FALSE
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@@ -97,5 +111,6 @@ Global
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{561BCA96-76DF-4A33-B767-4AD7CD3246B4} = {CEC0EC27-0CEC-90C6-CABA-E58AB278E4DA}
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{7237398A-2E8B-4161-BA15-DB090395A1F2} = {CEC0EC27-0CEC-90C6-CABA-E58AB278E4DA}
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{C9D46510-994A-4C43-BA8F-33CA9BED79D0} = {89C53051-77F9-4C1C-ABE5-6D54AB398471}
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{10A6FD3E-117A-4C9E-98E2-DAC31E7CE78A} = {89C53051-77F9-4C1C-ABE5-6D54AB398471}
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EndGlobalSection
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EndGlobal
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