How to use the grommet-icons.Next function in grommet-icons

daySize: baseSpacing * 32 / 7 + 'px',
        slideDuration: '0.8s'
      },
      icons: {
        previous: _grommetIcons.Previous,
        next: _grommetIcons.Next,
        small: {
          previous: _grommetIcons.FormPrevious,
          next: _grommetIcons.FormNext
        }
      }
    },
    carousel: {
      icons: {
        current: _grommetIcons.Subtract,
        next: _grommetIcons.Next,
        previous: _grommetIcons.Previous
        // color: undefined,
      }
    },
    checkBox: {
      border: {
        color: {
          dark: 'rgba(255, 255, 255, 0.5)',
          light: 'rgba(0, 0, 0, 0.15)'
        },
        radius: '4px',
        width: '2px'
      },
      check: {
        // color: { dark: undefined, light: undefined },
        width: '4px'

},
      medium: {
        fontSize: baseFontSize + 'px',
        lineHeight: 1.45,
        daySize: baseSpacing * 16 / 7 + 'px',
        slideDuration: '0.5s'
      },
      large: {
        fontSize: baseFontSize + fontScale + 'px',
        lineHeight: 1.11,
        daySize: baseSpacing * 32 / 7 + 'px',
        slideDuration: '0.8s'
      },
      icons: {
        previous: _grommetIcons.Previous,
        next: _grommetIcons.Next,
        small: {
          previous: _grommetIcons.FormPrevious,
          next: _grommetIcons.FormNext
        }
      }
    },
    carousel: {
      icons: {
        current: _grommetIcons.Subtract,
        next: _grommetIcons.Next,
        previous: _grommetIcons.Previous
        // color: undefined,
      }
    },
    checkBox: {
      border: {

pad: "xsmall",
      background: {
        color: 'white',
        opacity: 'medium'
      }
    }, _react["default"].createElement(_grommet.Text, null, axis[1][1]))))), _react["default"].createElement(_grommet.Box, {
      direction: "row",
      justify: "between"
    }, axis[0].map(function (t) {
      return _react["default"].createElement(_grommet.Text, {
        key: t,
        className: "chromatic-ignore"
      }, new Date(t).toLocaleDateString());
    }))), _react["default"].createElement(_grommet.Button, {
      hoverIndicator: true,
      icon: _react["default"].createElement(_grommetIcons.Next, null),
      onClick: function onClick() {
        return _this2.setState({
          reference: nextReference
        });
      }
    })));
  };

locale = _ref2.locale,
          onNextMonth = _ref2.onNextMonth,
          nextInBound = _ref2.nextInBound;
      return _react["default"].createElement(_grommet.Box, {
        direction: "row",
        align: "center",
        justify: "between"
      }, _react["default"].createElement(_grommetIcons.Blank, null), _react["default"].createElement(_grommet.Heading, {
        level: 3,
        margin: "none"
      }, currentDate.toLocaleDateString(locale, {
        month: 'long',
        year: 'numeric'
      })), _react["default"].createElement(_grommet.Button, {
        disabled: !nextInBound,
        icon: _react["default"].createElement(_grommetIcons.Next, null),
        onClick: onNextMonth
      }));
    }
  })));