C# events like object for Unity's coroutine

CoroutineEvent.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CoroutineEvent<T1, T2>
{
    public delegate IEnumerator CoroutineDelegate( T1 parameter1, T2 parameter2 );
    private readonly List<CoroutineDelegate> _eventHandlers = new List<CoroutineDelegate>();
    private int _runningCoroutinesCount;

    public void AddCoroutineDelegate( CoroutineDelegate coroutine )
    {
        _eventHandlers.Add( coroutine );
    }

    public bool RemoveCoroutineDelegate( CoroutineDelegate coroutine )
    {
        return _eventHandlers.Remove( coroutine );
    }

    public static CoroutineEvent<T1, T2> operator +( CoroutineEvent<T1, T2> self, CoroutineDelegate coroutine )
    {
        self.AddCoroutineDelegate( coroutine );
        return self;
    }

    public static CoroutineEvent<T1, T2> operator -( CoroutineEvent<T1, T2> self, CoroutineDelegate coroutine )
    {
        self.RemoveCoroutineDelegate( coroutine );
        return self;
    }

    public IEnumerator Coroutine( MonoBehaviour host, T1 parameter1, T2 parameter2 )
    {
        _runningCoroutinesCount = _eventHandlers.Count;
        foreach ( var eventCoroutine in _eventHandlers )
        {
            host.StartCoroutine( WrapCoroutine( host, eventCoroutine( parameter1, parameter2 ) ) );
        }
        while ( _runningCoroutinesCount > 0 )
        {
            yield return null;
        }
    }

    private IEnumerator WrapCoroutine( MonoBehaviour host, IEnumerator coroutine )
    {
        yield return host.StartCoroutine( coroutine );
        _runningCoroutinesCount--;
    }
}

public class CoroutineEvent<T>
{
    public delegate IEnumerator CoroutineDelegate( T parameter );
    private readonly List<CoroutineDelegate> _eventHandlers = new List<CoroutineDelegate>();
    private int _runningCoroutinesCount;

    public void AddCoroutineDelegate( CoroutineDelegate coroutine )
    {
        _eventHandlers.Add( coroutine );
    }

    public bool RemoveCoroutineDelegate( CoroutineDelegate coroutine )
    {
        return _eventHandlers.Remove( coroutine );
    }

    public static CoroutineEvent<T> operator +( CoroutineEvent<T> self, CoroutineDelegate coroutine )
    {
        self.AddCoroutineDelegate( coroutine );
        return self;
    }

    public static CoroutineEvent<T> operator -( CoroutineEvent<T> self, CoroutineDelegate coroutine )
    {
        self.RemoveCoroutineDelegate( coroutine );
        return self;
    }

    public IEnumerator Coroutine( MonoBehaviour host, T parameter )
    {
        _runningCoroutinesCount = _eventHandlers.Count;
        foreach ( var eventCoroutine in _eventHandlers )
        {
            host.StartCoroutine( WrapCoroutine( host, eventCoroutine( parameter ) ) );
        }
        while ( _runningCoroutinesCount > 0 )
        {
            yield return null;
        }
    }

    public bool HasHandlers()
    {
        return _eventHandlers.Count > 0;
    }

    private IEnumerator WrapCoroutine( MonoBehaviour host, IEnumerator coroutine )
    {
        yield return host.StartCoroutine( coroutine );
        _runningCoroutinesCount--;
    }
}

public class CoroutineEvent
{
    public delegate IEnumerator CoroutineDelegate();
    private readonly List<CoroutineDelegate> _eventHandlers = new List<CoroutineDelegate>();
    private int _runningCoroutinesCount;

    public void AddCoroutineDelegate( CoroutineDelegate coroutine )
    {
        _eventHandlers.Add( coroutine );
    }

    public bool RemoveCoroutineDelegate( CoroutineDelegate coroutine )
    {
        return _eventHandlers.Remove( coroutine );
    }

    public static CoroutineEvent operator +( CoroutineEvent self, CoroutineDelegate coroutine )
    {
        self.AddCoroutineDelegate( coroutine );
        return self;
    }

    public static CoroutineEvent operator -( CoroutineEvent self, CoroutineDelegate coroutine )
    {
        self.RemoveCoroutineDelegate( coroutine );
        return self;
    }

    public IEnumerator Coroutine( MonoBehaviour host )
    {
        _runningCoroutinesCount = _eventHandlers.Count;
        foreach ( var eventCoroutine in _eventHandlers )
        {
            host.StartCoroutine( WrapCoroutine( host, eventCoroutine() ) );
        }
        while ( _runningCoroutinesCount > 0 )
        {
            yield return null;
        }
    }

    public bool HasHandlers()
    {
        return _eventHandlers.Count > 0;
    }

    private IEnumerator WrapCoroutine( MonoBehaviour host, IEnumerator coroutine )
    {
        yield return host.StartCoroutine( coroutine );
        _runningCoroutinesCount--;
    }
}