ExtensionMethodAsyncTContext - делегат

public delegate Task ExtensionMethodAsync<in TContext>(
	TContext context
)
where TContext : class, IExtensionContext

Public Delegate Function ExtensionMethodAsync(Of In TContext As {Class, IExtensionContext}) ( 
	context As TContext
) As Task

generic<typename TContext>
where TContext : ref class, IExtensionContext
public delegate Task^ ExtensionMethodAsync(
	TContext context
)

type ExtensionMethodAsync = 
    delegate of 
        context : 'TContext -> Task