This function can be used to check whether the given vertex shader resource exists.
It's main purpose is for debugging to check if the resource has yet been created, has since been deleted or if the provided
resource identifier is invalid, such as would be the case for a mistyped variable name.

Return Boolean = DX11 VERTEX SHADER EXISTS(shader)

shader

Dword
The vertex shader resource to check whether it exists.

true if the given vertex shader resource exists, or false otherwise.

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