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

xxlarge: baseSpacing * 64 + "px",
        // 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,

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,
      line: {
        color: 'accent-1'

},
        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,
      line: {