Add a start of a few simple examples.

Change-Id: I6abd1798de6f2a778f874b8fa928772b94e7b588

docs/README.md

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+Documentation
+=============
+
+The start of documentation and examples about taskflow.
+
+*WIP*

docs/examples/reverting_linear.py

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+import logging
+import os
+import sys
+
+logging.basicConfig(level=logging.ERROR)
+
+if not os.path.isfile(os.path.join(os.getcwd(), "taskflow", '__init__.py')):
+    sys.path.insert(0, os.path.join(os.path.abspath(os.getcwd()), os.pardir))
+else:
+    sys.path.insert(0, os.path.abspath(os.getcwd()))
+
+from taskflow import decorators
+
+from taskflow.patterns import linear_flow as lf
+
+
+def undo_call(context, result, cause):
+    print("Calling %s and apologizing." % result)
+
+
+@decorators.task(revert_with=undo_call)
+def call_jim(context):
+    print("Calling jim.")
+    print("Context = %s" % (context))
+    return context['jim_number']
+
+
+@decorators.task(revert_with=undo_call)
+def call_joe(context):
+    print("Calling joe.")
+    print("Context = %s" % (context))
+    return context['joe_number']
+
+
+def call_suzzie(context):
+    raise IOError("Suzzie not home right now.")
+
+
+flow = lf.Flow("call-them")
+flow.add(call_jim)
+flow.add(call_joe)
+flow.add(call_suzzie)
+
+context = {
+    "joe_number": 444,
+    "jim_number": 555,
+}
+
+try:
+    flow.run(context)
+except Exception as e:
+    print("Flow failed: %s" % (e))

docs/examples/simple_linear.py

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+import logging
+import os
+import sys
+
+logging.basicConfig(level=logging.ERROR)
+
+if not os.path.isfile(os.path.join(os.getcwd(), "taskflow", '__init__.py')):
+    sys.path.insert(0, os.path.join(os.path.abspath(os.getcwd()), os.pardir))
+else:
+    sys.path.insert(0, os.path.abspath(os.getcwd()))
+
+from taskflow.patterns import linear_flow as lf
+
+
+def call_jim(context):
+    print("Calling jim.")
+    print("Context = %s" % (context))
+
+
+def call_joe(context):
+    print("Calling joe.")
+    print("Context = %s" % (context))
+
+
+flow = lf.Flow("call-them")
+flow.add(call_jim)
+flow.add(call_joe)
+
+context = {
+    "joe_number": 444,
+    "jim_number": 555,
+}
+flow.run(context)

docs/examples/simple_linear_listening.py

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+import logging
+import os
+import sys
+
+logging.basicConfig(level=logging.ERROR)
+
+if not os.path.isfile(os.path.join(os.getcwd(), "taskflow", '__init__.py')):
+    sys.path.insert(0, os.path.join(os.path.abspath(os.getcwd()), os.pardir))
+else:
+    sys.path.insert(0, os.path.abspath(os.getcwd()))
+
+from taskflow.patterns import linear_flow as lf
+
+
+def call_jim(context):
+    print("Calling jim.")
+    print("Context = %s" % (context))
+
+
+def call_joe(context):
+    print("Calling joe.")
+    print("Context = %s" % (context))
+
+
+def flow_watch(context, flow, old_state):
+    print("%s moved from %s => %s" % (flow, old_state, flow.state))
+
+
+def task_watch(context, state, flow, task, result=None):
+    print("%s of %s moved into state %s" % (task, flow, state))
+
+
+flow = lf.Flow("call-them")
+flow.add(call_jim)
+flow.add(call_joe)
+flow.task_listeners.append(task_watch)
+flow.listeners.append(flow_watch)
+
+context = {
+    "joe_number": 444,
+    "jim_number": 555,
+}
+flow.run(context)