public abstract Task<bool> DoesFileExistAsync(
	string parentPath,
	string fileName
)

Public MustOverride Function DoesFileExistAsync ( 
	parentPath As String,
	fileName As String
) As Task(Of Boolean)

public:
virtual Task<bool>^ DoesFileExistAsync(
	String^ parentPath, 
	String^ fileName
) abstract

abstract DoesFileExistAsync : 
        parentPath : string * 
        fileName : string -> Task<bool>