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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def bootstrap(
        platform,
        root,
        img_format='dir',
        fs_format='ext2',
        fs_opts=None,
        arch=None,
        flavor=None,
        repo_url=None,
        static_qemu=None,
        img_size=None,
        mount_dir=None,
        pkg_cache=None,
        pkgs=None,
        exclude_pkgs=None,
        epel_url=EPEL_URL,
    ):
    '''
    Create an image for a specific platform.

    Please note that this function *MUST* be run as root, as images that are
    created make files belonging to root.

    platform
        Which platform to use to create the image. Currently supported platforms
        are rpm, deb and pacman.

    root
        Local path to create the root of the image filesystem.

    img_format
        Which format to create the image in. By default, just copies files into
        a directory on the local filesystem (``dir``). Future support will exist
        for ``sparse``.

    fs_format
        When using a non-``dir`` ``img_format``, which filesystem to format the
        image to. By default, ``ext2``.

    fs_opts
        When using a non-``dir`` ``img_format``, a dict of opts may be
        specified.

    arch
        Architecture to install packages for, if supported by the underlying
        bootstrap tool. Currently only used for deb.

    flavor
        Which flavor of operating system to install. This correlates to a
        specific directory on the distribution repositories. For instance,
        ``wheezy`` on Debian.

    repo_url
        Mainly important for Debian-based repos. Base URL for the mirror to
        install from. (e.x.: http://ftp.debian.org/debian/)

    static_qemu
        Local path to the static qemu binary required for this arch.
        (e.x.: /usr/bin/qemu-amd64-static)

    pkg_confs
        The location of the conf files to copy into the image, to point the
        installer to the right repos and configuration.

    img_size
        If img_format is not ``dir``, then the size of the image must be
        specified.

    mount_dir
        If img_format is not ``dir``, then the image must be mounted somewhere.
        If the ``mount_dir`` is not specified, then it will be created at
        ``/opt/salt-genesis.<random_uuid>``. This directory will be unmounted
        and removed when the process is finished.

    pkg_cache
        This points to a directory containing a cache of package files to be
        copied to the image. It does not need to be specified.

    pkgs
        A list of packages to be installed on this image. For RedHat, this
        will include ``yum``, ``centos-release`` and ``iputils`` by default.

    exclude_pkgs
        A list of packages to be excluded. If you do not want to install the
        defaults, you need to include them in this list.

    epel_url
        The URL to download the EPEL release package from.

    CLI Examples:

    .. code-block:: bash

        salt myminion genesis.bootstrap pacman /root/arch
        salt myminion genesis.bootstrap rpm /root/redhat
        salt myminion genesis.bootstrap deb /root/wheezy arch=amd64 \
            flavor=wheezy static_qemu=/usr/bin/qemu-x86_64-static

    '''
    if img_format not in ('dir', 'sparse'):
        raise SaltInvocationError('The img_format must be "sparse" or "dir"')

    if img_format == 'dir':
        # We can just use the root as the root
        if not __salt__['file.directory_exists'](root):
            try:
                __salt__['file.mkdir'](root)
            except Exception as exc:
                return {'Error': salt.utils.stringutils.to_unicode(pprint.pformat(exc))}
    elif img_format == 'sparse':
        if not img_size:
            raise SaltInvocationError('An img_size must be specified for a sparse file')
        if not mount_dir:
            mount_dir = '/opt/salt-genesis.{0}'.format(uuid.uuid4())
        __salt__['file.mkdir'](mount_dir, 'root', 'root', '755')
        __salt__['cmd.run'](('fallocate', '-l', img_size, root), python_shell=False)
        _mkpart(root, fs_format, fs_opts, mount_dir)

        loop1 = __salt__['cmd.run']('losetup -f')
        log.debug('First loop device is %s', loop1)
        __salt__['cmd.run']('losetup {0} {1}'.format(loop1, root))
        loop2 = __salt__['cmd.run']('losetup -f')
        log.debug('Second loop device is %s', loop2)
        start = six.text_type(2048 * 2048)
        __salt__['cmd.run']('losetup -o {0} {1} {2}'.format(start, loop2, loop1))
        __salt__['mount.mount'](mount_dir, loop2)

        _populate_cache(platform, pkg_cache, mount_dir)

    if mount_dir:
        root = mount_dir

    if pkgs is None:
        pkgs = []

    if exclude_pkgs is None:
        exclude_pkgs = []

    if platform in ('rpm', 'yum'):
        _bootstrap_yum(
            root,
            pkgs=pkgs,
            exclude_pkgs=exclude_pkgs,
            epel_url=epel_url,
        )
    elif platform == 'deb':
        _bootstrap_deb(
            root,
            arch=arch,
            flavor=flavor,
            repo_url=repo_url,
            static_qemu=static_qemu,
            pkgs=pkgs,
            exclude_pkgs=exclude_pkgs,
        )
    elif platform == 'pacman':
        _bootstrap_pacman(
            root,
            img_format=img_format,
            pkgs=pkgs,
            exclude_pkgs=exclude_pkgs,
        )

    if img_format != 'dir':
        blkinfo = __salt__['disk.blkid'](loop2)
        __salt__['file.replace'](
            '{0}/boot/grub/grub.cfg'.format(mount_dir),
            'ad4103fa-d940-47ca-8506-301d8071d467',  # This seems to be the default
            blkinfo[loop2]['UUID']
        )
        __salt__['mount.umount'](root)
        __salt__['cmd.run']('losetup -d {0}'.format(loop2))
        __salt__['cmd.run']('losetup -d {0}'.format(loop1))
        __salt__['file.rmdir'](mount_dir)