def build_from_reader(self, reader):
        self.reserved = reader.read_words("reserved", "evlr")
        self.user_id = "".join(reader.read_words("user_id", "evlr"))
        self.record_id = reader.read_words("record_id", "evlr")
        self.rec_len_after_header = reader.read_words("rec_len_after_header", "evlr")
        self.description = "".join(reader.read_words("description", "evlr"))
        self.VLR_body = reader.read(self.rec_len_after_header)
        if self.user_id == "LASF_Spec" and self.record_id == 4:
            self.setup_extra_bytes_spec(self.VLR_body)

        ### LOGICAL CONTENT ###
        self.isEVLR = True
        self.fmt = reader.evlr_formats
        try:
            self.parse_data()
        except Exception, err:
            print("Error Parsing EVLR Body Data:")
            print(err)
Build an evlr from a reader capable of reading in the data.
dataset/ETHPy150Open grantbrown/laspy/laspy/header.py/EVLR.build_from_reader