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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 render_field(parser, token):
 """ Render a form field using given attribute-value pairs Takes form field as first argument and list of attribute-value pairs for all other arguments. Attribute-value pairs should be in the form of attribute=value or attribute="a value" for assignment and attribute+=value or attribute+="value" for appending. """

    error_msg = '%r tag requires a form field followed by a list of attributes and values in the form attr="value"' % token.split_contents()[0]
    try:
        bits = token.split_contents()
        tag_name = bits[0]
        form_field = bits[1]
        attr_list = bits[2:]
    except ValueError:
        raise TemplateSyntaxError(error_msg)

    form_field = parser.compile_filter(form_field)

    set_attrs = []
    append_attrs = []
    for pair in attr_list:
        match = ATTRIBUTE_RE.match(pair)
        if not match:
            raise TemplateSyntaxError(error_msg + ": %s" % pair)
        dct = match.groupdict()
        attr, sign, value = \
            dct['attr'], dct['sign'], parser.compile_filter(dct['value'])
        if sign == "=":
            set_attrs.append((attr, value))
        else:
            append_attrs.append((attr, value))

    return FieldAttributeNode(form_field, set_attrs, append_attrs)