Revert "Restructured the operators source files and added support for multiple new operators. (#70)" (#108)

This reverts commit d2c78f4.

Author: rxwei

Sources/DeepLearning/DifferentialOperators.swift

@@ -13,20 +13,12 @@
 // limitations under the License.
 
 #if !COMPILING_TENSORFLOW_MODULE
-@_exported import TensorFlow
+import TensorFlow
 #endif
 
-/// Returns a tensor with the same shape and scalars as the specified tensor.
-@inlinable
-@differentiable
-public func identity<Scalar>(_ x: Tensor<Scalar>) -> Tensor<Scalar> {
-    return x
-}
-
 // `pow` is defined in Darwin/Glibc on `Float` and `Double`, but there doesn't exist a generic
 // version for `FloatingPoint`.
 // This is a manual definition.
-@inlinable
-func pow<T: BinaryFloatingPoint>(_ x: T, _ y: T) -> T {
+func pow<T : BinaryFloatingPoint>(_ x: T, _ y: T) -> T {
     return T(pow(Double(x), Double(y)))
 }