docs: def add_alpha_labels(axes, xpos=0.03, ypos=0.95, suffix='', color=None,
          fontsize=14, fontweight='normal', boxstyle='square', facecolor='white',
          edgecolor='white', alpha=1.0):
      '''Add sequential alphbet labels to subplot axes
  
      Args
      ----
      axes: list of pyplot.ax
          A list of matplotlib axes to add the label labels to
      xpos: float or array_like
          X position(s) of labels in figure coordinates
      ypos: float or array_like
          Y position(s) of labels in figure coordinates
      suffix: str
          String to append to labels (e.g. '.' or ' name)
      color: matplotlib color
          Color of labels
      fontsize: int
          Alppa fontsize
      fontweight: matplotlib fontweight
          Alpha fontweight
      boxstyle: matplotlib boxstyle
          Alpha boxstyle
      facecolor: matplotlib facecolor
          Color of box containing label
      edgecolor: matplotlib edgecolor
          Color of box'es border containing label
      alpha: float
          Transparency of label
  
      Returns
      -------
      axes: list of pyplot.ax
          A list of matplotlib axes objects with alpha labels added
      '''
      import seaborn
      import string
      import numpy
  
      if not numpy.iterable(xpos):
          xpos = [xpos,]*len(axes)
          ypos = [ypos,]*len(axes)
  
      if (len(xpos) > 1) or (len(ypos) > 1):
          try:
              assert (len(axes) == len(xpos))
          except AssertionError as e:
              e.args += 'xpos iterable must be same length as axes'
              raise
          try:
              assert (len(axes) == len(ypos))
          except AssertionError as e:
              e.args += 'ypos iterable must be same length as axes'
              raise
      else:
          xpos = [xpos,]
          ypos = [ypos,]
  
      colors = seaborn.color_palette()
      abc = string.ascii_uppercase
  
      for i, (label, ax) in enumerate(zip(abc[:len(axes)], axes)):
          if color is None:
              color = colors[i]
          kwargs = dict(color=color,
                        fontweight=fontweight,)
  
          bbox = dict(boxstyle=boxstyle,
                       facecolor=facecolor,
                       edgecolor=edgecolor,
                       alpha=alpha)
  
          ax.text(xpos[i], ypos[i], '{}{}'.format(label, suffix),
                  transform=ax.transAxes, fontsize=fontsize,
                  verticalalignment='top', bbox=bbox, **kwargs)
      return axes