diff --git a/src/kyupy/__init__.py b/src/kyupy/__init__.py
index fd6ab26..897e832 100644
--- a/src/kyupy/__init__.py
+++ b/src/kyupy/__init__.py
@@ -6,6 +6,7 @@ if they are available and otherwise point to mocks.
 """
 
 import time
+import sys
 from collections import defaultdict
 import importlib.util
 import gzip
@@ -76,21 +77,27 @@ def hr_time(seconds):
 
 
 class Timer:
-    def __init__(self): self.s = 0
-    def __enter__(self): self.start_time = time.perf_counter()
+    def __init__(self, s=0): self.s = s
+    def __enter__(self): self.start_time = time.perf_counter(); return self
     def __exit__(self, *args): self.s += time.perf_counter() - self.start_time
     @property
     def ms(self): return self.s*1e3
     @property
     def us(self): return self.s*1e6
-    def __repr__(self): return f'{self.s:.3f}s' if self.s >= 1 else f'{self.ms:.3f}ms'
+    def __repr__(self): return f'{self.s:.3f}'
+    def __add__(self, t):
+        return Timer(self.s + t.s)
 
 
 class Timers:
-    def __init__(self): self.timers = defaultdict(Timer)
+    def __init__(self, t={}): self.timers = defaultdict(Timer) | t
     def __getitem__(self, name): return self.timers[name]
     def __getattr__(self, name): return self.timers[name]
-    def __repr__(self): return ''.join([f'{k}={v} ' for k, v in self.timers.items()])
+    def __repr__(self): return '{' + ', '.join([f'{k}: {v}' for k, v in self.timers.items()]) + '}'
+    def __add__(self, t):
+        tmr = Timers(self.timers)
+        for k, v in t.timers.items(): tmr.timers[k] += v
+        return tmr
 
 
 class Log:
@@ -100,25 +107,36 @@ class Log:
 
     def __init__(self):
         self.start = time.perf_counter()
-        self.logfile = None
+        self.logfile = sys.stdout
         """When set to a file handle, log messages are written to it instead to standard output.
         After each write, ``flush()`` is called as well.
         """
+        self.indent = 0
 
     def __getstate__(self):
         return {'elapsed': time.perf_counter() - self.start}
 
     def __setstate__(self, state):
-        self.logfile = None
+        self.logfile = sys.stdout
+        self.indent = 0
         self.start = time.perf_counter() - state['elapsed']
 
+    def write(self, s, indent=0):
+        self.logfile.write(' '*indent + s + '\n')
+        self.logfile.flush()
+
+    def li(self, item): self.write('- ' + str(item).replace('\n', '\n'+' '*(self.indent+1)), self.indent)
+    def lib(self): self.write('-', self.indent); self.indent += 1
+    def lin(self): self.write('-', self.indent-1)
+    def di(self, key, value): self.write(str(key) + ': ' + str(value).replace('\n', '\n'+' '*(self.indent+1)), self.indent)
+    def dib(self, key): self.write(str(key) + ':', self.indent); self.indent += 1
+    def din(self, key): self.write(str(key) + ':', self.indent-1)
+    def ie(self, n=1): self.indent -= n
+
     def log(self, level, message):
         t = time.perf_counter() - self.start
-        if self.logfile is None:
-            print(f'{t:011.3f} {level} {message}')
-        else:
-            self.logfile.write(f'{t:011.3f} {level} {message}\n')
-            self.logfile.flush()
+        self.logfile.write(f'# {t:011.3f} {level} {message}\n')
+        self.logfile.flush()
 
     def info(self, message):
         """Log an informational message."""
@@ -227,11 +245,11 @@ if importlib.util.find_spec('numba') is not None:
     try:
         list(numba.cuda.gpus)
         from numba import cuda
+        from numba.core import config
+        config.CUDA_LOW_OCCUPANCY_WARNINGS = False
     except CudaSupportError:
         log.warn('Cuda unavailable. Falling back to pure Python.')
         cuda = MockCuda()
-    from numba.core import config
-    config.CUDA_LOW_OCCUPANCY_WARNINGS = False
 else:
     numba = MockNumba()
     """If Numba is available on the system, it is the actual ``numba`` package.