@classmethod
def from_http_header(cls, header_value, sampled):
    """

        Root=1-5759e988-bd862e3fe1be46a994272793;Parent=53995c3f42cd8ad8;Sampled=1

        """
    parts = header_value.lower().split(';')
    data = {'sampled': '1' if sampled else '0'}
    for part in parts:
        subparts = part.split('=', 1)
        if len(subparts) == 2:
            data[subparts[0]] = subparts[1]
    root = data.get('root')
    parent = data.get('parent')
    sampled = data.get('sampled') == '1'
    return cls(root=root, parent=parent, sampled=sampled)
