ソースコード

using System.Collections.Generic;

public static class DictionaryExtensions
{
    public static bool ContainsKeyNullable<TKey, TValue>( 
        this Dictionary<TKey, TValue> self, TKey key 
    )
    {
        if ( key == null )
        {
            return false;
        }
        return self.ContainsKey( key );
    }
}

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