def parse_encoding_header(header):
    """
    Break up the `HTTP_ACCEPT_ENCODING` header into a dict of the form,
    {'encoding-name':qvalue}.
    """
    encodings = {'identity': 1.0}
    for encoding in header.split(','):
        if encoding.find(';') > -1:
            encoding, qvalue = encoding.split(';')
            encoding = encoding.strip()
            qvalue = qvalue.split('=', 1)[1]
            if qvalue != '':
                encodings[encoding] = float(qvalue)
            else:
                encodings[encoding] = 1
        else:
            encodings[encoding] = 1
    return encodings
