ds3231_simple:12: Error: 'ds3231 clock' redeclared as different kind of symbol
 ds3231 clock;
        ^
in file included from c:\users\lenovo\appdata\local\arduino15\packages\a  rduino\tools\arm-none-eabi-gcc\4.8.3-2014q1\arm-none-eabi\include\stdlib.h:11:0,
                 from c:\users\lenovo\appdata\local\arduino15\packages\a  rduino\hardware\sam\1.6.7\cores\arduino/arduino.h:24,
                 from sketch\ds3231_simple.ino.cpp:1:
C:\users\lenovo\appdata\local\arduino15\packages\a  rduino\tools\arm-none-eabi-gcc\4.8.3-2014q1\arm-none-eabi\include\time.h:44:12: Error: Previous declaration of 'clock_t clock()'
 clock_t    _exfun(clock,    (void));
            ^
c:\users\lenovo\desktop\arduino ide\libraries\arduino-ds3231-master\ds3231_simple\ds3231_simple.ino: In function 'void setup()':
Ds3231_simple:21: Error: Request for member 'begin' in 'clock', which is of non-class type 'clock_t() {aka long unsigned int()}'
   clock.begin();
         ^
ds3231_simple:24: Error: Request for member 'setdatetime' in 'clock', which is of non-class type 'clock_t() {aka long unsigned int()}'
   clock.setdatetime(__date__, __time__);
         ^
c:\users\lenovo\desktop\arduino ide\libraries\arduino-ds3231-master\ds3231_simple\ds3231_simple.ino: In function 'void loop()':
Ds3231_simple:29: Error: Request for member 'getdatetime' in 'clock', which is of non-class type 'clock_t() {aka long unsigned int()}'
   dt = clock.getdatetime();
              ^
exit status 1
'ds3231 clock' redeclared as different kind of symbol