vbo.buffer nor vbo.buffers aren't normally used by external code
The normal way to get the ID of the VBO is int(vbo)
See https://github.com/inducer/pyopencl/issues/196

Using type suffix

Fixing CompilerWarning: <program source>: warning: double precision constant requires cl_khr_fp64, casting to single precision
An application that wants to use double will need to include the directive before any double precision data type is declared in the kernel code.