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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 parse_address(netloc, default_port=8000):
    '''Parse an internet address ``netloc`` and return a tuple with
``host`` and ``port``.'''
    if isinstance(netloc, tuple):
        if len(netloc) != 2:
            raise ValueError('Invalid address %s' % str(netloc))
        return netloc
    #
    netloc = native_str(netloc)
    auth = None
    # Check if auth is available
    if '@' in netloc:
        auth, netloc = netloc.split('@')
    if netloc.startswith("unix:"):
        host = netloc.split("unix:")[1]
        return '%s@%s' % (auth, host) if auth else host
    # get host
    if '[' in netloc and ']' in netloc:
        host = netloc.split(']')[0][1:].lower()
    elif ':' in netloc:
        host = netloc.split(':')[0].lower()
    elif netloc == "":
        host = "0.0.0.0"
    else:
        host = netloc.lower()
    # get port
    netloc = netloc.split(']')[-1]
    if ":" in netloc:
        port = netloc.split(':', 1)[1]
        if not port.isdigit():
            raise ValueError("%r is not a valid port number." % port)
        port = int(port)
    else:
        port = default_port
    return ('%s@%s' % (auth, host) if auth else host, port)