---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[64], line 8
      5 y = x.reshape(-1, 1)
      6 h = x * y
----> 8 cs = plt.contour(h, levels=[10, 30, 50],
      9     colors='green', extend='both')

File ~/miniconda3/envs/sklearn-env/lib/python3.12/site-packages/matplotlib/pyplot.py:3143, in contour(data, *args, **kwargs)
   3141 @_copy_docstring_and_deprecators(Axes.contour)
   3142 def contour(*args, data=None, **kwargs) -> QuadContourSet:
-> 3143     __ret = gca().contour(
   3144         *args, **({"data": data} if data is not None else {}), **kwargs
   3145     )
   3146     if __ret._A is not None:  # type: ignore[attr-defined]
   3147         sci(__ret)

File ~/miniconda3/envs/sklearn-env/lib/python3.12/site-packages/matplotlib/__init__.py:1473, in _preprocess_data.<locals>.inner(ax, data, *args, **kwargs)
   1470 @functools.wraps(func)
   1471 def inner(ax, *args, data=None, **kwargs):
   1472     if data is None:
-> 1473         return func(
   1474             ax,
   1475             *map(sanitize_sequence, args),
   1476             **{k: sanitize_sequence(v) for k, v in kwargs.items()})
   1478     bound = new_sig.bind(ax, *args, **kwargs)
   1479     auto_label = (bound.arguments.get(label_namer)
   1480                   or bound.kwargs.get(label_namer))

File ~/miniconda3/envs/sklearn-env/lib/python3.12/site-packages/matplotlib/axes/_axes.py:6659, in Axes.contour(self, *args, **kwargs)
   6650 """
   6651 Plot contour lines.
   6652 
   (...)
   6656 %(contour_doc)s
   6657 """
   6658 kwargs['filled'] = False
-> 6659 contours = mcontour.QuadContourSet(self, *args, **kwargs)
   6660 self._request_autoscale_view()
   6661 return contours

File ~/miniconda3/envs/sklearn-env/lib/python3.12/site-packages/matplotlib/contour.py:847, in ContourSet.__init__(self, ax, levels, filled, linewidths, linestyles, hatches, alpha, origin, extent, cmap, colors, norm, vmin, vmax, extend, antialiased, nchunk, locator, transform, negative_linestyles, clip_path, *args, **kwargs)
    845             cmap.set_under(self.colors[0])
    846         if self._extend_max:
--> 847             cmap.set_over(self.colors[-1])
    849 # label lists must be initialized here
    850 self.labelTexts = []

File ~/miniconda3/envs/sklearn-env/lib/python3.12/site-packages/matplotlib/colors.py:834, in Colormap.set_over(self, color, alpha)
    832 def set_over(self, color='k', alpha=None):
    833     """Set the color for high out-of-range values."""
--> 834     self._rgba_over = to_rgba(color, alpha)
    835     if self._isinit:
    836         self._set_extremes()

File ~/miniconda3/envs/sklearn-env/lib/python3.12/site-packages/matplotlib/colors.py:314, in to_rgba(c, alpha)
    312     rgba = None
    313 if rgba is None:  # Suppress exception chaining of cache lookup failure.
--> 314     rgba = _to_rgba_no_colorcycle(c, alpha)
    315     try:
    316         _colors_full_map.cache[c, alpha] = rgba

File ~/miniconda3/envs/sklearn-env/lib/python3.12/site-packages/matplotlib/colors.py:391, in _to_rgba_no_colorcycle(c, alpha)
    387             raise ValueError(
    388                 f"Invalid string grayscale value {orig_c!r}. "
    389                 f"Value must be within 0-1 range")
    390         return c, c, c, alpha if alpha is not None else 1.
--> 391     raise ValueError(f"Invalid RGBA argument: {orig_c!r}")
    392 # turn 2-D array into 1-D array
    393 if isinstance(c, np.ndarray):

ValueError: Invalid RGBA argument: 'n'