text: # Copyright (c) 2016, BRML
  # All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are met:
  #
  # 1. Redistributions of source code must retain the above copyright notice,
  # this list of conditions and the following disclaimer.
  #
  # 2. Redistributions in binary form must reproduce the above copyright notice,
  # this list of conditions and the following disclaimer in the documentation
  # and/or other materials provided with the distribution.
  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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  # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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  # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  # POSSIBILITY OF SUCH DAMAGE.
  
  
  class MotionPlanner(object):
      def __init__(self):
          """Base class for a motion planner.
          A motion planner should have at least
            - a field telling the controller which type of control it plans for
              (<'position', 'velocity', 'torque'>) and
            - a method implementing the planning algorithm as a generator. Each
              iteration should yield a dictionary of <joint name, Cartesian
              coordinate> keys to <joint angle, joint velocity, joint torque,
              coordinate> values.
          """
          self.controller_type = ''
          self._trajectory = None
  
      def __iter__(self):
          if self._trajectory is None:
              raise RuntimeError("Need to plan a trajectory first!")
          for t in self._trajectory:
              yield t
  
      def plan(self, start, end, **kwargs):
          """A generator implementing the planning algorithm."""
          raise NotImplementedError()
  