def _rgba(color: Color, alpha: int) -> Color:
"""
Args:
color: may be an RGB or RGBA color
"""
assert color.startswith('#') and len(color) in (7, 9), f'invalid RGB color: "{color}"'
assert 0 <= alpha < 255, f'alpha out of range: {alpha}'
return f'{color[:7]}{alpha:02x}'
def set_color_alpha(color: Color, alpha: int) -> Color:
"""
Args:
color: may be an RGB or RGBA hex color string
alpha: the new alpha value (0-255)
"""
assert color.startswith('#') and len(color) in (
7, 9), f'invalid RGB color: "{color}"'
assert 0 <= alpha < 255, f'alpha out of range: {alpha}'
return f'{color[:7]}{alpha:02x}'
def set_color_alpha(color: Color, alpha: int) -> Color:
""" Returns `color` including the new `alpha` channel in hex format:
"#RRGGBBAA".
Args:
color: may be an RGB or RGBA hex color string
alpha: the new alpha value (0-255)
"""
assert color.startswith('#') and len(color) in (
7, 9), f'invalid RGB color: "{color}"'
assert 0 <= alpha < 256, f'alpha out of range: {alpha}'
return f'{color[:7]}{alpha:02x}'
