def METHOD_NAME(self):
    token = ''
    while self.current_char.isdigit():
        token += self.current_char
        self.advance()
    if self.current_char == Token.DOT:
        token += Token.DOT
        self.advance()
        while self.current_char.isdigit():
            token += self.current_char
            self.advance()
        return self.build_token(float(token), Token.FLOAT_CONST)
    else:
        return self.build_token(int(token), Token.INT_CONST)