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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def colorize(string, rgb=None, ansi=None, bg=None, ansi_bg=None, fd=1):
    '''Returns the colored string to print on the terminal.

    This function detects the terminal type and if it is supported and the
    output is not going to a pipe or a file, then it will return the colored
    string, otherwise it will return the string without modifications.

    string = the string to print. Only accepts strings, unicode strings must
             be encoded in advance.
    rgb    = Rgb color for the text; for example 0xFF0000 is red.
    ansi   = Ansi for the text
    bg     = Rgb color for the background
    ansi_bg= Ansi color for the background
    fd     = The file descriptor that will be used by print, by default is the
             stdout
    '''

    #Reinitializes if fd used is different
    if colorize.fd != fd:
        colorize.init = False
        colorize.fd = fd

    #Checks if it is on a terminal, and if the terminal is recognized
    if not colorize.init:
        colorize.init = True
        colorize.is_term = isatty(fd)
        if 'TERM' in environ:
            if environ['TERM'].startswith('xterm'):
                colorize.cmap = XTermColorMap()
            elif environ['TERM'] == 'vt100':
                colorize.cmap = VT100ColorMap()
            else:
                colorize.is_term = False
        else:
            colorize.is_term = False

    if colorize.is_term:
        string = colorize.cmap.colorize(string, rgb, ansi, bg, ansi_bg)

    return string