How to use the @material-ui/utils.deepmerge function in @material-ui/utils

if (!color.contrastText) {
      color.contrastText = getContrastText(color.main);
    }

    return color;
  }

  const types = { dark, light };

  if (process.env.NODE_ENV !== 'production') {
    if (!types[type]) {
      console.error(`Material-UI: the palette type \`${type}\` is not supported.`);
    }
  }

  const paletteOutput = deepmerge(
    {
      // A collection of common colors.
      common,
      // The palette type, can be light or dark.
      type,
      // The colors used to represent primary interface elements for a user.
      primary: augmentColor(primary),
      // The colors used to represent secondary interface elements for a user.
      secondary: augmentColor(secondary, 'A400', 'A200', 'A700'),
      // The colors used to represent interface elements that the user should be made aware of.
      error: augmentColor(error),
      // The colors used to represent potentially dangerous actions or important messages.
      warning: augmentColor(warning),
      // The colors used to present information to the user that is neutral and not necessarily important.
      info: augmentColor(info),
      // The colors used to indicate the successful completion of an action that user triggered.

h1: buildVariant(fontWeightLight, 96, 1.167, -1.5),
    h2: buildVariant(fontWeightLight, 60, 1.2, -0.5),
    h3: buildVariant(fontWeightRegular, 48, 1.167, 0),
    h4: buildVariant(fontWeightRegular, 34, 1.235, 0.25),
    h5: buildVariant(fontWeightRegular, 24, 1.334, 0),
    h6: buildVariant(fontWeightMedium, 20, 1.6, 0.15),
    subtitle1: buildVariant(fontWeightRegular, 16, 1.75, 0.15),
    subtitle2: buildVariant(fontWeightMedium, 14, 1.57, 0.1),
    body1: buildVariant(fontWeightRegular, 16, 1.5, 0.15),
    body2: buildVariant(fontWeightRegular, 14, 1.43, 0.15),
    button: buildVariant(fontWeightMedium, 14, 1.75, 0.4, caseAllCaps),
    caption: buildVariant(fontWeightRegular, 12, 1.66, 0.4),
    overline: buildVariant(fontWeightRegular, 12, 2.66, 1, caseAllCaps),
  };

  return deepmerge(
    {
      htmlFontSize,
      pxToRem,
      round, // TODO To remove in v5?
      fontFamily,
      fontSize,
      fontWeightLight,
      fontWeightRegular,
      fontWeightMedium,
      fontWeightBold,
      ...variants,
    },
    other,
    {
      clone: false, // No need to clone deep
    },

function merge(acc, item) {
  if (!item) {
    return acc;
  }

  return deepmerge(acc, item, {
    clone: false, // No need to clone deep, it's way faster.
  });
}

function createMuiTheme(options = {}, ...args) {
  const {
    breakpoints: breakpointsInput = {},
    mixins: mixinsInput = {},
    palette: paletteInput = {},
    spacing: spacingInput,
    typography: typographyInput = {},
    ...other
  } = options;

  const palette = createPalette(paletteInput);
  const breakpoints = createBreakpoints(breakpointsInput);
  const spacing = createSpacing(spacingInput);

  let muiTheme = deepmerge(
    {
      breakpoints,
      direction: 'ltr',
      mixins: createMixins(breakpoints, spacing, mixinsInput),
      overrides: {}, // Inject custom styles
      palette,
      props: {}, // Provide default props
      shadows,
      typography: createTypography(palette, typographyInput),
      spacing,
      shape,
      transitions,
      zIndex,
    },
    other,
  );

Object.keys(overrides).forEach(key => {
        if (process.env.NODE_ENV !== 'production') {
          if (!stylesWithOverrides[key]) {
            console.warn(
              [
                'Material-UI: you are trying to override a style that does not exist.',
                `Fix the \`${key}\` key of \`theme.overrides.${name}\`.`,
              ].join('\n'),
            );
          }
        }

        stylesWithOverrides[key] = deepmerge(stylesWithOverrides[key], overrides[key]);
      });

  muiTheme = args.reduce((acc, argument) => deepmerge(acc, argument), muiTheme);