function output = plot(obj,varargin)
  % Call a ShoulderCase.shoulder.plot function.
  %
  % input: (''), ('manual'), ('auto')
  %        input arguments are not case sensitive.
  %
  % output: call obj.shoulderManual.plot (default) or obj.shoulderAuto.plot.

  assert(nargin <= 2,'Too many arguments given')
  if nargin == 1
    output = obj.shoulderManual.plot;
    return
  end
  assert(ischar(varargin{1}),'Given argument must be a char array')
  shoulderToPlot = lower(varargin{1}); % given argument is not case sensitive
  if isequal(shoulderToPlot,'manual')
    output = obj.shoulderManual.plot;
  elseif isequal(shoulderToPlot,'auto')
    output = obj.shoulderAuto.plot;
  else
    error('Wrong type of shoulder given. Input must be ''manual'' or ''auto''.');
  end
end