docs: def setup():
      """import the matplotlib modules and set the style
  
      Returns
      -------
      plt: pylab
          imported pylab module
      mpl: matplotlib module
          imported matplotlib module
  
      """
      # Latex support can be activated using an environment variable, otherwise
      # the default settings are:
      # - for windows: off
      # - else: on
      use_latex = False
      if('DD_USE_LATEX' in os.environ):
          if os.environ['DD_USE_LATEX'] == '1':
              use_latex = True
      else:
          if platform.system() == "Windows":
              use_latex = False
          else:
              use_latex = True
  
      already_loaded = 'matplotlib' in sys.modules
  
      # just make sure we can access matplotlib as mpl
      import matplotlib as mpl
  
      if not already_loaded:
          mpl.use('Agg')
  
      import matplotlib.pyplot as plt
  
      plt.style.use('seaborn')
  
      # general settings
      mpl.rcParams['font.size'] = 7.0
      mpl.rcParams['axes.labelsize'] = 7.0
      mpl.rcParams['xtick.labelsize'] = 7.0
      mpl.rcParams['ytick.labelsize'] = 7.0
      mpl.rcParams["lines.linewidth"] = 1.5
      mpl.rcParams["lines.markeredgewidth"] = 3.0
      mpl.rcParams["lines.markersize"] = 3.0
      # mpl.rcParams['font.sans-serif'] = 'Droid Sans'
  
      # mpl.rcParams['font.family'] = 'Open Sans'
      # mpl.rcParams['font.weight'] = 400
      mpl.rcParams['mathtext.default'] = 'regular'
  
      # mpl.rcParams['font.family'] = 'Droid Sans'
  
      if use_latex:
          mpl.rcParams['text.usetex'] = True
  
          mpl.rc(
              'text.latex',
              preamble=''.join((
                  # r'\usepackage{droidsans}',
                  # r'\usepackage[T1]{fontenc} ',
                  r'\usepackage{sfmath} \renewcommand{\rmfamily}{\sffamily}',
                  r'\renewcommand\familydefault{\sfdefault} ',
                  # r'\usepackage{mathastext} '
              ))
          )
      else:
          mpl.rcParams['text.usetex'] = False
      import mpl_toolkits.axes_grid1 as axes_grid1
      axes_grid1
      return plt, mpl