A value that is either an AnvilTensor, can be converted to it, or
represents an abstract version of it.
This also includes atomic R vectors.
Examples
x <- nv_tensor(1:4, dtype = "f32")
x
#> AnvilTensor
#> 1.0000
#> 2.0000
#> 3.0000
#> 4.0000
#> [ CPUf32{4} ]