def __init__(self, user_id, record_id, VLR_body, **kwargs):
        self.user_id = str(user_id) + "\x00"*(16-len(str(user_id)))
        self.record_id = record_id
        self.VLR_body = VLR_body
        self.body_fmt = None

        try: 
            self.rec_len_after_header = len(self.VLR_body) 
        except(TypeError):
            self.rec_len_after_header = 0
        if "description" in kwargs:
            self.description = str(kwargs["description"]) + "\x00"*(32-len(kwargs["description"]))
        else:
            self.description = "\x00"*32
        if "reserved" in kwargs:
            self.reserved = kwargs["reserved"]
        else:
            self.reserved = 0 
        self.fmt = util.Format("EVLR")
        self.isEVLR = True
        self.type = 0
        if self.user_id == "LASF_Spec" and self.record_id == 4:
            self.setup_extra_bytes_spec(self.VLR_body)
        try:
            self.parse_data()
        except Exception, err:
            print("Error Parsing EVLR Body Data:")
            print(err)
Build the EVLR using the required arguments user_id, record_id, and
dataset/ETHPy150Open grantbrown/laspy/laspy/header.py/EVLR.__init__