How to use the grommet-icons/icons/FormDown.FormDown function in grommet-icons

size: 'xsmall'
        },
        pad: {
          horizontal: 'small',
          vertical: 'xsmall'
        }
      },
      groupEnd: {
        border: {
          side: 'bottom',
          size: 'xsmall'
        }
      },
      header: {},
      icons: {
        ascending: _FormDown.FormDown,
        contract: _FormUp.FormUp,
        descending: _FormUp.FormUp,
        expand: _FormDown.FormDown
      },
      primary: {
        weight: 'bold'
      },
      resize: {
        border: {
          color: 'border',
          side: 'right'
        }
      }
    },
    diagram: {
      // extend: undefined,

border: 'horizontal',
        pad: {
          horizontal: 'medium',
          vertical: 'small'
        } // extend: undefined,

      } // extend: undefined,

    },
    maskedInput: {// extend: undefined,
    },
    menu: {
      // background: undefined,
      // extend: undefined,
      icons: {
        down: _FormDown.FormDown
      }
    },
    meter: {
      color: 'accent-1' // colors: [],
      // extend: undefined,

    },
    paragraph: {
      small: _extends({}, fontSizing(-1)),
      medium: _extends({}, fontSizing(0)),
      large: _extends({}, fontSizing(1)),
      xlarge: _extends({}, fontSizing(2)),
      xxlarge: _extends({}, fontSizing(4))
    },
    radioButton: {
      border: {

// 1536
        full: '100%'
      }
    },
    accordion: {
      border: {
        side: 'bottom',
        color: 'border'
      },
      heading: {
        level: '4'
      },
      // level ranges from 1-6
      icons: {
        collapse: _FormUp.FormUp,
        expand: _FormDown.FormDown // color: { dark: undefined, light: undefined },

      }
    },
    anchor: {
      textDecoration: 'none',
      fontWeight: 600,
      color: {
        dark: 'accent-1',
        light: 'brand'
      },
      hover: {
        textDecoration: 'underline' // fontWeight: undefined,
        // extend: undefined,

      } // extend: undefined,

horizontal: 'small',
          vertical: 'xsmall'
        }
      },
      groupEnd: {
        border: {
          side: 'bottom',
          size: 'xsmall'
        }
      },
      header: {},
      icons: {
        ascending: _FormDown.FormDown,
        contract: _FormUp.FormUp,
        descending: _FormUp.FormUp,
        expand: _FormDown.FormDown
      },
      primary: {
        weight: 'bold'
      },
      resize: {
        border: {
          color: 'border',
          side: 'right'
        }
      }
    },
    diagram: {
      // extend: undefined,
      line: {
        color: 'accent-1'
      }