docs: def matplot(x, y, z, ax=None, colorbar=True, **kwargs):
      """ Plot x, y, z as expected with correct axis labels.
  
      Examples
      --------
      >>> import matplotlib.pyplot as plt
      >>> import numpy as np
      >>> from reda.plotters import matplot
      >>> a = np.arange(4)
      >>> b = np.arange(3) + 3
      >>> def sum(a, b):
      ...    return a + b
      >>> x, y = np.meshgrid(a, b)
      >>> c = sum(x, y)
      >>> fig, (ax1, ax2) = plt.subplots(1, 2)
      >>> im = ax1.pcolormesh(x, y, c)
      >>> _ = plt.colorbar(im, ax=ax1)
      >>> _ = ax1.set_title("plt.pcolormesh")
      >>> _, _ = matplot(x, y, c, ax=ax2)
      >>> _ = ax2.set_title("reda.plotters.matplot")
      >>> fig.show()
  
      Note
      ----
      Only works for equidistant data at the moment.
      """
      xmin = x.min()
      xmax = x.max()
      dx = np.abs(x[0, 1] - x[0, 0])
  
      ymin = y.min()
      ymax = y.max()
      dy = np.abs(y[1, 0] - y[0, 0])
  
      x2, y2 = np.meshgrid(
          np.arange(xmin, xmax + 2 * dx, dx) - dx / 2.,
          np.arange(ymin, ymax + 2 * dy, dy) - dy / 2.)
  
      if not ax:
          fig, ax = plt.subplots()
      else:
          fig = ax.figure
  
      im = ax.pcolormesh(x2, y2, z, **kwargs)
      ax.axis([x2.min(), x2.max(), y2.min(), y2.max()])
      ax.set_xticks(np.arange(xmin, xmax + dx, dx))
      ax.set_yticks(np.arange(ymin, ymax + dx, dy))
  
      if colorbar:
          cbar = fig.colorbar(im, ax=ax)
      else:
          cbar = None
  
      return ax, cbar