code: def remove_nan_observations(x, y, z):
      r
      x_ = x[~np.isnan(z)]
      y_ = y[~np.isnan(z)]
      z_ = z[~np.isnan(z)]
  
      return x_, y_, z_
docs: r"""Remove all x, y, and z where z is nan.
  
      Will not destroy original values.
  
      Parameters
      ----------
      x: array_like
          x coordinate
      y: array_like
          y coordinate
      z: array_like
          observation value
  
      Returns
      -------
      x, y, z
          List of coordinate observation pairs without
          nan valued observations.