Added comments.

Author: isazi

kernel_tuner/backends/backend.py

@@ -5,6 +5,7 @@
 
 
 class Backend(ABC):
+    """Base class for kernel_tuner backends"""
     @abstractmethod
     def ready_argument_list(self, arguments):
         pass
@@ -47,6 +48,7 @@ def memcpy_htod(self, dest, src):
 
 
 class GPUBackend(Backend):
+    """Base class for GPU backends"""
     @abstractmethod
     def __init__(self, device, iterations, compiler_options, observers):
         pass
@@ -65,6 +67,7 @@ def copy_texture_memory_args(self, texmem_args):
 
 
 class CompilerBackend(Backend):
+    """Base class for compiler backends"""
     @abstractmethod
     def __init__(self, iterations, compiler_options, compiler):
         pass