def rgb_to_hex(r, g, b, a=None, bg=255, prefix="#"):
    """
    Convert given RGB color decimals or floats to Hex string.

    Parameters
    ---
    r, g, b: float | int
        Corresponding channel value. Support decimal or float.

    a: float | None, Default: None
        Alpha value for generate simulated transparent color.
        If specified, the returned hex color should looks like
        rendered as `a` alpha value, on the given background `bg`.
        Default to None, which means disable simuating transparent.

    bg: int, Default: 255
        If `a` is specified, `bg` will be used as the background
        for render transparent color.
        Default to 255, which means 'white' background.

    Examples
    ---
    >>> rgb_to_hex(255, 0, 255)
    '#FF00FF'

    >>> rgb_to_hex(255, 255, 0, a=0.0625, bg=0)
    '#0F0F00'
    """

    def to_decimal(v, base=255) -> int:
        if isinstance(v, float) and v <= 1:
            v *= base
        return int(v)

    def patch_alpha(v, alpha, bg=255):
        return int(v * alpha + bg * (1 - alpha))

    r = to_decimal(r)
    g = to_decimal(g)
    b = to_decimal(b)

    if a is not None:
        r = patch_alpha(r, a, bg)
        g = patch_alpha(g, a, bg)
        b = patch_alpha(b, a, bg)

    if prefix is None:
        prefix = ""

    return f"{prefix}{r:02X}{g:02X}{b:02X}"