Function alloc_value 

pub unsafe extern "C" fn alloc_value(
    context: *mut c_context,
    state: *mut EvalState,
) -> *mut value

@brief Allocate a Nix value @ingroup value_create

Call nix_value_decref() when you’re done with the pointer @param[out] context Optional, stores error information @param[in] state nix evaluator state @return value, or null in case of errors