Merge branch 'feature/elementwise_checks_part_2' of https://github.com/peterwicksstringfield/math into feature/elementwise_checks_part_2

Author: bbbales2

stan/math/opencl/kernel_generator/load.hpp

@@ -52,7 +52,7 @@ class load_
    * Creates a deep copy of this expression.
    * @return copy of \c *this
    */
-  inline load_<T&> deep_copy() const & { return load_<T&>(a_); }
+  inline load_<T&> deep_copy() const& { return load_<T&>(a_); }
   inline load_<T> deep_copy() && { return load_<T>(std::forward<T>(a_)); }
 
   /**