def parse_image_format(s: Optional[str]) -> str:
from matplotlib.backend_bases import FigureCanvasBase
if not is_set(s):
return FigureCanvasBase.get_default_filetype()
assert isinstance(s, str)
_, _, ext = s.rpartition(".")
if ext not in (available :=
list(FigureCanvasBase.get_supported_filetypes().keys())):
raise ValueError(f"Received unknown file format '{s}'. "
f"Available formated are {available}.")
